Zoloto

What's Changed
* PDF center line by RealOrangeOne in https://github.com/RealOrangeOne/zoloto/pull/297
* Allow numpy versions over 1.21 by RealOrangeOne in https://github.com/RealOrangeOne/zoloto/pull/298
* Add support for Python 3.10 by RealOrangeOne in https://github.com/RealOrangeOne/zoloto/pull/299
* Drop support for Python 3.7


**Full Changelog**: https://github.com/RealOrangeOne/zoloto/compare/0.8.0...0.9.0

Some big internal changes:

What's Changed
* Ensure calibration resolution matches camera by RealOrangeOne in https://github.com/RealOrangeOne/zoloto/pull/292
* Fix marker pdf sizes by RealOrangeOne in https://github.com/RealOrangeOne/zoloto/pull/293
* Add command to validate calibrations by RealOrangeOne in https://github.com/RealOrangeOne/zoloto/pull/291
* Drop Python 3.6


**Full Changelog**: https://github.com/RealOrangeOne/zoloto/compare/0.7.1...0.8.0

A patch release, but still quite a few additions:

- Add some documentation around calibration
- Add a CLI command to output marker images (`save-markers`)
- Remove default marker type on preview
- Add CLI command for showing details of all marker types (`marker-details`)
- Add CLI command to save marker images to A4 PDFs (`marker-pdfs`)
- Add CLI command to annotate markers in video
- Add reprs to marker and cameras

Note: Some of the new commands require additional dependencies to run. These can be installed with the `cli` extra. If these commands are not used, the dependencies aren't required.

One chonker of a release! Notable changes include:

- Drop support for Python 3.5 (255)
- Remove the need to subclass cameras before using them (220)
- Allow using the system installed version of OpenCV, making it an optional dependencies (281)
- Move examples to a CLI, so they can be consumed
- Define just 1 marker type per ArUco size (284)
- Add support for OpenCV >4.1 and Python >3.8 (285)
- Remove built-in JSON decoding
- Remove runtime dependency on setuptools
- Use OpenCVs built-in viewer rather than tkinter
- Add some extra attributes on `MarkerType`

- Fix issue with `Camera` cameras being "completely broken" (221)

- Rename `marker_dict` to `marker_type` (154 )
- Make _some_ cameras iterable (155 )
- Refactor marker class (mostly internal changes) (150 )
- Re-raise OpenCV exceptions (162 )