gh-134716: Support regular expressions in -W and PYTHONWARNINGS

[serhiy-storchaka]

• Issue: Support regular expressions in -W and PYTHONWARNINGS #134716

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📚 Documentation preview 📚: https://cpython-previews--138149.org.readthedocs.build/

[vstinner]

LGTM

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot s390x RHEL8 LTO + PGO 3.x (tier-3) has failed when building commit cf9ef73.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/442/builds/10220) and take a look at the build logs.
4. Check if the failure is related to this commit (cf9ef73) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/442/builds/10220

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-rhel8-s390x.lto-pgo/build/Lib/contextlib.py", line 112, in __init__
    doc = getattr(func, "__doc__", None)
ValueError: flush of closed file
Warning -- Unraisable exception
Exception ignored while finalizing file <_io.BufferedWriter>:
Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-rhel8-s390x.lto-pgo/build/Lib/contextlib.py", line 112, in __init__
    doc = getattr(func, "__doc__", None)
ValueError: flush of closed file
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