Remove use of Python 3.9 in tests against dandi-cli

[candleindark]

As of dandi/dandi-cli#1759, dandi-cli has drop support of Python 3.9, so testing against dandi-cli in a Python 3.9 environment is no longer relevant and causes the following error.

This PR removes the use of Python 3.9 in integration tests against dandi-cli.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.89%. Comparing base (f6e5aa6) to head (a1a4783).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #359   +/-   ##
=======================================
  Coverage   97.89%   97.89%           
=======================================
  Files          18       18           
  Lines        2377     2377           
=======================================
  Hits         2327     2327           
  Misses         50       50           

Flag	Coverage Δ
unittests	97.89% <ø> (ø)

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[Copilot]

Pull request overview

This PR updates the dandi-cli integration test workflow to remove Python 3.9 support, aligning with dandi-cli's recent decision to drop Python 3.9 in their PR #1759.

Key Changes:

• Removed Python 3.9 from the test matrix includes
• Updated dandi-devel test entries to use Python 3.10 instead
• Removed obsolete exclude section for Windows + Python 3.9

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