Add regression test for Bitbucket commits paging

[n4p68vc6p9-hub]

Summary

• Add regression coverage for repository commits iteration in Bitbucket Cloud
• Ensure commits.each() wraps the paged commit payload directly instead of fetching each commit again by hash
• Covers the failure mode reported in [Bitbucket] repository.commits.each() -> Expected type of data is [commit], got [None] #1071, where the extra lookup could return None and break Commit construction

Tests

• python -m pytest tests\test_bitbucket_cloud_oo.py -q -o addopts=