Nbconvert

The full list of changes can be seen on the [6.2.0
milestone](https://github.com/jupyter/nbconvert/milestone/21?closed=1)

- Add the ability to fully customize `widget_renderer_url`
[1614](https://github.com/jupyter/nbconvert/pull/1614)
- Enable users to customize MathJax URLs [1609](https://github.com/jupyter/nbconvert/pull/1609)
- Add CLI configuration for disable-chromium-sandbox
[1625](https://github.com/jupyter/nbconvert/pull/1625)
- Enables webpdf to be rendered with templates
[1601](https://github.com/jupyter/nbconvert/pull/1601)
- Adds dejavu [1599](https://github.com/jupyter/nbconvert/pull/1599)

This release is mostly a long list of bug fixes and capability
additions. Thanks to the many contributors for helping Improve
nbconvert!

The following 31 authors contributed 81 commits.

- Adolph
- Alessandro Finamore
- Angus Hollands
- Atsuo Ishimoto
- Bo
- David Brochart
- Frédéric Collonval
- Jeremy Howard
- Jim Zwartveld
- José Ignacio Romero
- Joyce Er
- joyceerhl
- Kyle Cutler
- Leah E. Cole
- Leah Wasser
- Nihiue
- Matthew Seal
- Michael Adolph
- Mohammad Mostafa Farzan
- Okky Mabruri
- Pill-GZ
- ptcane
- Raniere Silva
- Ryan Moe
- Stefan Lang
- Sylvain Corlay
- Tobin Jones
- txoof
- Yuvi Panda

Significant Changes

- Dropped Python 3.6 and added Python 3.9 [1542](https://github.com/jupyter/nbconvert/pull/1542) and [#1556](https://github.com/jupyter/nbconvert/pull/1556)
- Convert execute preprocessor wrapper to resemble papermill
[1448](https://github.com/jupyter/nbconvert/pull/1448)

Comprehensive notes

- Feature: support static widgets in Reveal.js slides
[1553](https://github.com/jupyter/nbconvert/pull/1553)
- Feature: add speaker notes to Reveal.js template
[1543](https://github.com/jupyter/nbconvert/pull/1543)
- Add correct output mimetype to WebPDF exporter
[1534](https://github.com/jupyter/nbconvert/pull/1534)
- Set mimetype for webpdf correctly [1514](https://github.com/jupyter/nbconvert/pull/1514)
- Fix docstring issue and a broken link [1576](https://github.com/jupyter/nbconvert/pull/1576)
- Add CLI example for removing cell tag syntax
[1504](https://github.com/jupyter/nbconvert/pull/1504)
- Include output of stdin stream in lab template
[1454](https://github.com/jupyter/nbconvert/pull/1454)
- Don't use a shell to call inkscape [1512](https://github.com/jupyter/nbconvert/pull/1512)
- JupyterLab export as HTML with widgets fails to load widgets
[1474](https://github.com/jupyter/nbconvert/pull/1474)
- Move note inside Reveal.js HTML slideshow [1510](https://github.com/jupyter/nbconvert/pull/1510)
- fix issue 1507: broken command line option
--CSSHTMLHeaderPreprocessor.style= [1548](https://github.com/jupyter/nbconvert/pull/1548)
- Fix order of template paths [1496](https://github.com/jupyter/nbconvert/pull/1496)
- Changed documentation of external_exporters [1582](https://github.com/jupyter/nbconvert/pull/1582)
- Fix template precedence when using a custom template (1558)
[1577](https://github.com/jupyter/nbconvert/pull/1577)
- add pip to docs envt [1571](https://github.com/jupyter/nbconvert/pull/1571)
- Fix CI By Adding PIP to conda envt for docs build
[1570](https://github.com/jupyter/nbconvert/pull/1570)
- Explicitly install pip in docs environment.yml
[1569](https://github.com/jupyter/nbconvert/pull/1569)
- small update to docs hide cell [1567](https://github.com/jupyter/nbconvert/pull/1567)
- Allow child templates to override mathjax [1551](https://github.com/jupyter/nbconvert/pull/1551)
- Allow get_export_names to skip configuration check
[1471](https://github.com/jupyter/nbconvert/pull/1471)
- Update docs: Tex Live package on Ubuntu [1555](https://github.com/jupyter/nbconvert/pull/1555)
- Test jupyter_client [1545](https://github.com/jupyter/nbconvert/pull/1545)
- Update jupyterlab css [1539](https://github.com/jupyter/nbconvert/pull/1539)
- Webpdf: Use a temporary file instead of an URL
[1489](https://github.com/jupyter/nbconvert/pull/1489)
- Applied patch for marking network changes [1527](https://github.com/jupyter/nbconvert/pull/1527)
- Change webpdf display name [1515](https://github.com/jupyter/nbconvert/pull/1515)
- Allow disabling pyppeteer sandbox [1516](https://github.com/jupyter/nbconvert/pull/1516)
- Make pagination configurable in webpdf [1513](https://github.com/jupyter/nbconvert/pull/1513)
- Fix Reveal.js version in documentation [1509](https://github.com/jupyter/nbconvert/pull/1509)
- Fix dangling reference to get_template_paths()
[1463](https://github.com/jupyter/nbconvert/pull/1463)
- Solved svg2pdf conversion error if Inkscape is installed into the
default path on a windows machine [1469](https://github.com/jupyter/nbconvert/pull/1469)
- fix typo [1499](https://github.com/jupyter/nbconvert/pull/1499)
- Update version dependency of traitlets [1498](https://github.com/jupyter/nbconvert/pull/1498)
- Update execute.py [1457](https://github.com/jupyter/nbconvert/pull/1457)
- Fix code output indentation when running nbconvert --no-input
[1444](https://github.com/jupyter/nbconvert/pull/1444)
- fix issue (i'd call it a BUG) 1167 [1450](https://github.com/jupyter/nbconvert/pull/1450)
- 1428 add docstring [1433](https://github.com/jupyter/nbconvert/pull/1433)
- Update nbconvert_library.ipynb [1438](https://github.com/jupyter/nbconvert/pull/1438)
- Supports isolated iframe when converting to HTML
[1593](https://github.com/jupyter/nbconvert/pull/1593)

Primarily a release addressing template extensions issues reported since
6.0 launched.

Comprehensive notes

- Comment typo fix [1425](https://github.com/jupyter/nbconvert/pull/1425)
- Documented updated to default conversion changes from 6.0
[1426](https://github.com/jupyter/nbconvert/pull/1426)
- Allow custom template files outside of the template system to set
their base template name [1429](https://github.com/jupyter/nbconvert/pull/1429)
- Restored basic template from 5.x [1431](https://github.com/jupyter/nbconvert/pull/1431)
- Added proper support for backwards compatibility templates
[1431](https://github.com/jupyter/nbconvert/pull/1431)

A range of bug fixes for webpdf exports

Comprehensive notes

- Removed CSS preprocessor from default proprocessor list (fixes
classic rendering) [1411](https://github.com/jupyter/nbconvert/pull/1411)
- Fixed error when pickling TemplateExporter [1399](https://github.com/jupyter/nbconvert/pull/1399)
- Support for fractional height html / webpdf exports
[1413](https://github.com/jupyter/nbconvert/pull/1413)
- Added short wait time for fonts and rendering in webpdf
[1414](https://github.com/jupyter/nbconvert/pull/1414)
- Updated template documentation
- Minor fixes to the webpdf exporter [1419](https://github.com/jupyter/nbconvert/pull/1419)
- Fixup use with a running event loop within webpdf
[1420](https://github.com/jupyter/nbconvert/pull/1420)
- Prevent overflow in input areas in lab template
[1422](https://github.com/jupyter/nbconvert/pull/1422)

- Revert networkidle2 change which caused custom cdn-fetched widgets
in webpdf

Comprehensive notes

Fixing Problems

- The webpdf exporters does not add pagebreaks anymore before reaching
the maximum height allowed by Adobe [1402](https://github.com/jupyter/nbconvert/pull/1402)
- Fixes some timeout issues with the webpdf exporter
[1400](https://github.com/jupyter/nbconvert/pull/1400)