Avoid pyav v14 to prevent AttributeError #1418

Job	Run time
Linting	22s
No-Internet Install	31s
CPython Test Suite / ubuntu-latest / CPython 3.9	2m 25s
CPython Test Suite / ubuntu-latest / CPython 3.10	2m 20s
CPython Test Suite / ubuntu-latest / CPython 3.11	2m 14s
CPython Test Suite / ubuntu-latest / CPython 3.12	2m 22s
CPython Test Suite / macos-latest / CPython 3.9	2m 48s
CPython Test Suite / macos-latest / CPython 3.10	2m 52s
CPython Test Suite / macos-latest / CPython 3.11	2m 20s
CPython Test Suite / macos-latest / CPython 3.12	2m 23s
CPython Test Suite / windows-latest / CPython 3.9	3m 31s
CPython Test Suite / windows-latest / CPython 3.10	3m 12s
Build Docs / Build Docs	25s
CPython Test Suite / windows-latest / CPython 3.12	3m 33s
PyPy Test Suite / ubuntu-latest / pypy-3.10	1m 49s
PyPy Test Suite / macos-latest / pypy-3.10	3m 34s
	36m 41s

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