Make a duplicate fixture for pandas dtypes including pyarrow types

[weiji14]

Description of proposed changes

Explicitly copying the numpy dtypes fixture in test_clib_virtualfiles.py to a new dtypes_pandas fixture that includes pyarrow types, so that modifications to the original numpy dtypes fixture won't affect other tests.

Fixes #2936 (comment)

Reminders

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• Add tests for new features or tests that would have caught the bug that you're fixing.
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• Write detailed docstrings for all functions/methods.
• If wrapping a new module, open a 'Wrap new GMT module' issue and submit reasonably-sized PRs.
• If adding new functionality, add an example to docstrings or tutorials.
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