Allow ValidationExceptionGroup to propagate through context managers

[renan-r-santos]

ValidationExceptionGroup was a frozen dataclass. When raised inside a context manager, contextlib's __exit__ assigns exc.__traceback__ at the Python level as the exception unwinds, and the frozen __setattr__ rejected it masking the real error. Ordinary propagation was unaffected because the interpreter sets the traceback at the C level, bypassing __setattr__.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.61%. Comparing base (910a810) to head (cf15a07).
⚠️ Report is 1 commits behind head on master.
❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #57      +/-   ##
==========================================
+ Coverage   92.45%   92.61%   +0.16%     
==========================================
  Files          34       35       +1     
  Lines        1524     1558      +34     
  Branches      232      234       +2     
==========================================
+ Hits         1409     1443      +34     
  Misses         50       50              
  Partials       65       65              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.