Upgrade PyAV because it blocks support for Python 3.14

[cclauss]

Fixes: #4494

• #4494

Related to

• #4037
• #4385
• #4493

% uvx --with=av python3.14 -c "import av" # Works as expected. -- https://pypi.org/project/av

Overview: What does this pull request change?

Upgrade PyAV because it blocks support for Python 3.14

Motivation and Explanation: Why and how do your changes improve the library?

https://www.python.org/downloads/release/python-3140/

= 64 failed, 781 passed, 2 skipped, 7 xfailed, 1 xpassed, 21 warnings in 738.29s (0:12:18) =

Links to added or changed documentation pages

Further Information and Comments

Reviewer Checklist

• [ ] The PR title is descriptive enough for the changelog, and the PR is labeled correctly
• [ ] If applicable: newly added non-private functions and classes have a docstring including a short summary and a PARAMETERS section
• [ ] If applicable: newly added functions and classes are tested

@behackl

[behackl]

Appreciate the gesture, the pyav version upgrade unfortunately comes with a few interface changes that require some more changes. I've started this in #4385, should be ready soon.