Increase `asdf-wcs-schemas` version

[braingram]

asdf-wcs-schemas 0.4.0 was released.

This PR increases the minimum required version to 0.4.0.

As https://github.com/spacetelescope/gwcs/pull/488 is not yet released the changelog entry was updated to point to this PR.

~Additionally this PR adds an upper pin for pytest (as a test dependency) as the newest version 8.1.1 is incompatible with pytest-doctestplus (see https://github.com/scientific-python/pytest-doctestplus/issues/243).~ EDIT: a new version of pytest-doctestplus was released that fixed the issue

Finally, this PR also increases the minimum tested numpy to 1.23 (the oldest supported version at this time, see: https://numpy.org/neps/nep-0029-deprecation_policy.html#support-table).

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 87.28%. Comparing base (eb9d316) to head (cdaa38a). Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #491 +/- ## ======================================= Coverage 87.28% 87.28% ======================================= Files 22 22 Lines 3821 3823 +2 ======================================= + Hits 3335 3337 +2 Misses 486 486 ```

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