Update pydantic dependency to >= 2

[dvzrv]

Check List

Resolves: #

• [ ] I added tests for the changed code.
• [ ] I updated the documentation for the changed code.
• [x] I ran the full tox test suite locally, so the CI pipelines should be green.
• [x] I added the change to the CHANGELOG.md file.

I tried adapting the code for pydantic >= 2. However, there are still weird warnings in the docs-* tox targets that I can not figure out, so those will likely fail.

WARNING: Failed guarded type import with ImportError("cannot import name 'AbstractSetIntStr' from 'pydantic._internal._utils' (/home/user/rstcheck-core/.tox/docs/lib/python3.11/site-packages/pydantic/_internal/_utils.py)")

AFAICT, the type in question is not directly used in this code base but might be dragged in by something else. I can't figure out from where and how to not have the tox targets fail on this. Some feedback would be greatly appreciated!

Closes #44

[dvzrv]

cc @polyzen

[Cielquan]

Will try to take a look on it soon.

[hojo0590]

In case you need more time to figure this out pydantic offers v1 support even in versions greater 2.0.
So for a 'quick compatibility fix' you could go for from pydantic import v1 as pydantic (see their Readme) and tackle this in the near future.

[Cielquan]

I think we should give it a bit more time before dropping support for v1. Therefore the approach suggested by @hojo0590 would be better. I guess an Import-Try-Except for the pydantic stuff would be the best way to implement this.

I would push the drop of v1 support to the end of this year. This should be plenty of time.

[Cielquan]

I just resolved the changelog merge conflict real quick.