Improve project skeleton (pykeen#1418)

This PR does the following:

1. Switches from `setup.cfg` to `pyproject.toml`
2. Switches from black/isort/flake8 to using ruff
3. Updates the tox.ini
4. Adds backwards compatibility for using `pkg_resources` for plugin
loading (will need to reinvestigate later when adding modern python
support)
5. Remove `sphinx_autodoc_typehints` and make minor updates to improve
sphinx. Still need in future PR to switch to newest sphinx
6. Make appropriate updates to CONTRIBUTING.md
7. Switch tests to tox-uv backend for tox, there are also other ways to
speed things up with caching further

Author: cthoyt

.bumpversion.cfg

@@ -26,3 +26,7 @@ replace = VERSION = "{new_version}"
 [bumpversion:file:docs/source/conf.py]
 search = release = "{current_version}"
 replace = release = "{new_version}"
+
+[bumpversion:file:pyproject.toml]
+search = version = "{current_version}"
+replace = version = "{new_version}"