Improve native parser version mismatch errors

[cyphercodes]

Summary

Fixes #21412.

When parallel checking is used with an incompatible ast-serialize version, mypy now reports a clear blocking error instead of surfacing an internal error from the native parser worker path.

Test Plan

• pytest -n0 -q mypy/test/test_nativeparse.py::TestNativeParserBinaryFormat
• pytest -n0 -q mypy/test/test_nativeparse.py
• python -m mypy --config-file mypy_self_check.ini mypy/parse.py mypy/nativeparse.py mypy/test/test_nativeparse.py
• pre-commit run --files mypy/nativeparse.py mypy/parse.py mypy/test/test_nativeparse.py
• git diff --check

Also smoke-tested ast-serialize==0.2.0 with python -m mypy -n2 --no-incremental ... and confirmed it now reports an incompatible-version error instead of an INTERNAL ERROR, then restored ast-serialize==0.3.0 and reran the parallel smoke successfully.

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅