Add GitHub Actions workflow for PyPI trusted publishing

[ubaskota]

Issue #, if available:

Description of changes:
Adds a GitHub Actions workflow for publishing botocore to PyPI using trusted publishing (OIDC). This replaces credential-based publishing with a more secure, token-free approach where PyPI verifies the package origin directly through GitHub's OIDC identity.

Testing
Ran a test build and verified that a package was published to test.pypi as expected.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.56%. Comparing base (ee748e4) to head (d0a5e28).
⚠️ Report is 224 commits behind head on develop.
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Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3716      +/-   ##
===========================================
- Coverage    92.59%   92.56%   -0.03%     
===========================================
  Files           68       68              
  Lines        15634    15773     +139     
===========================================
+ Hits         14477    14601     +124     
- Misses        1157     1172      +15     

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