[BUG] Meta issue: Cython 0.29.x is not compatible with Python 3.10

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I created the issue as a meta issue for Cython 0.29.x compatibility issues with Python 3.10.

Bugs:

• [BUG] Tests failing on Python 3.10: annotations as string and no more empty frozenset singleton #3919: Tests failing on Python 3.10: annotations as string and no more empty frozenset singleton
• [BUG] Cython 0.29.22 SIGSEGV with Python 3.10.0a6 #4025: Cython 0.29.22 SIGSEGV with Python 3.10.0a6 [BUG] Cython 0.29.22 SIGSEGV with Python 3.10.0a6 #4025

Fixes:

• Port test_exceptions to Python 3.10 #4042: Port test_exceptions to Python 3.10
• Port test_asyncgen to Python 3.10 #4044: Port test_asyncgen to Python 3.10
• Make load_dynamic() compatible with Python 3.10 #4045: Make load_dynamic() compatible with Python 3.10

See also #4027 ( Decimal module C API) and #4029 (Structural Pattern Matching) which are feature requests, not compatibility issues.

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Fedora downstream issue: https://bugzilla.redhat.com/show_bug.cgi?id=1939885

[scoder]

All issues closed and PRs merged.