Py-pdf-parser

Added
- Added support for opening password protected files ([350](https://github.com/jstockwin/py-pdf-parser/pull/350))

Changed
- Various dependency updates
- PyPI releases now use Trusted Publishers

Fixed
- Fixed typo in docs ([361](https://github.com/jstockwin/py-pdf-parser/pull/361))

Changed
- Various dependency updates
- Removed unused PyYAML dependency ([262](https://github.com/jstockwin/py-pdf-parser/pull/262))

Fixed
- The `visualise` function properly uses the _elements_ parameter in order to filter visualised elements. ([256](https://github.com/jstockwin/py-pdf-parser/pull/256))

Changed
- Various dependency updates

- [BREAKING] Changes from using pyqt5 to using tkinter for the visualise tool. This
means we don't need the python3-dev as a requirement, and seems to solve endless
issues with pyqt5 not finding the correct qt bindings. This is a potential breaking
change, although the visualise tool is only in the development version. No code
changes are needed, but you will need tkinter installed for visualise to still work.
- Changed python version from 3.6 to 3.8 in `.readthedocs.yml`.

Changed
- Various dependency updates (matplotlib, pyqt5)
- Removed all but the tests dockerfile for simplicity. Use Docker BuildKit. We will no longer be pushing images to DockerHub on release. ([203](https://github.com/jstockwin/py-pdf-parser/pull/203))