Fix build failure

[jeffjennings]

The tests on main are currently failing, and the setup.cfg is causing problems for the learn-astropy CI that depends on this package. This PR gets the tests passing and updates setup.cfg. Changes:

• Updates requirements in setup.cfg:

  • Update version of dependency async_timeout - based on this algolia .toml
  • In dev requirements, replace types-pkg_resources (deprecated, see here) with types-setuptools

• Uses pydantic.v1 throughout code, where previously a couple outlier instances of pydantic were used (which was causing multiple problems in tests)

• Updates python versions for tests

• Skips typing and linter CI steps, as there are several (probably benign) typing complaints and the linter step was just force-running pre-commit with a github action that is no longer being updated (.pre-commit-config.yaml is still present in the repo). These steps can be uncommented in the workflow .yaml in the future if desired.

[kelle]

Looks AMAZING to me! Thanks so much for working on this!

[pllim]

Just one comment. Otherwise LGTM.

p.s. In the future, please open PRs from your fork. Thanks!