ignore addressed attrs deprecation warning in oldestdeps

[braingram]

The newest version of attrs includes a deprecation warning for a feature used in asdf: https://github.com/python-attrs/attrs/releases/tag/24.1.0 This has been addressed: https://github.com/asdf-format/asdf/pull/1815 and released in asdf 3.4.0 https://github.com/asdf-format/asdf/releases/tag/3.4.0

However the oldestdeps job here will not pick up the change until the minimum asdf version is 3.4.0. This is because the oldest deps job only installs the oldest versions of direct dependencies (like asdf) and will install the newest version of indirect deps (like attrs).

This PR adds a warning filter to ignore the warning from attrs.

Checklist

• [ ] Added entry in CHANGES.rst under the corresponding subsection
• [ ] updated relevant tests
• [ ] updated relevant documentation
• [ ] Passed romancal regression testing on Jenkins / PLWishMaster. Link: https://plwishmaster.stsci.edu:8081/job/RT/job/romancal/XXX/

[codecov[bot]]

Codecov Report

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

Project coverage is 97.66%. Comparing base (087a60d) to head (f167029). Report is 34 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #371 +/- ## ========================================== + Coverage 97.56% 97.66% +0.10% ========================================== Files 30 36 +6 Lines 2788 3335 +547 ========================================== + Hits 2720 3257 +537 - Misses 68 78 +10 ```

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