Fix ClassVar forward ref inherited from parent class

[alexmojaki]

Change Summary

Make the hack in is_classvar work for strings like 'typing.ClassVar[...]', not just 'ClassVar[...]'.

Related issue number

Fixes #9069

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

[codspeed-hq]

CodSpeed Performance Report

Merging #9097 will not alter performance

_{Comparing alex/inherit-pydantic_parent_namespace (31779cd) with main (f794f65)}

Summary

✅ 10 untouched benchmarks

[sydney-runkle]

Great, thanks!