update test to allow easier deprecation of `ignore_version_mismatch`

[braingram]

This PR adds a filter to ignore a deprecation warning for an upcoming asdf deprecation: https://github.com/asdf-format/asdf/pull/1819 ignore_version_mismatch has done nothing since asdf 3.0.0. However it is currently set in stdatamodels: https://github.com/spacetelescope/stdatamodels/pull/313 Deprecating the feature in asdf will cause 1 jwst test to fail which turns all warnings into errors: https://github.com/spacetelescope/jwst/blob/89f126a035751674f29a9027e2deae11b3e63fca/jwst/assign_wcs/tests/test_schemas.py#L57 This PR ignores the upcoming deprecation warning to allow the test to continue to pass. The trigger for the warning is being addressed in the above stdatamodels PR but would otherwise require a new stdatamodels release (with the above PR). Filtering this warning seems like an easier option.

Checklist for PR authors (skip items if you don't have permissions or they are not applicable)

• [ ] added entry in CHANGES.rst within the relevant release section
• [ ] updated or added relevant tests
• [ ] updated relevant documentation
• [ ] added relevant milestone
• [ ] added relevant label(s)
• [ ] ran regression tests, post a link to the Jenkins job below. How to run regression tests on a PR
• [ ] All comments are resolved
• [ ] Make sure the JIRA ticket is resolved properly

[codecov[bot]]

Codecov Report

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

Project coverage is 60.38%. Comparing base (f6c4095) to head (ccef809).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #8693 +/- ## ======================================= Coverage 60.38% 60.38% ======================================= Files 372 372 Lines 38337 38337 ======================================= Hits 23148 23148 Misses 15189 15189 ```

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