gh-108962: Skip test_tempfile.test_flags() if not supported

[vstinner]

Skip test_tempfile.test_flags() if chflags() fails with "OSError: [Errno 45] Operation not supported" (ex: on FreeBSD 13).

• Issue: test_tempfile.test_flags() fails on FreeBSD: Operation not supported #108962

[vstinner]

@zware tested manually on the buildbot machine and reported to me that this change fix test_tempfile.

I tested manually on my FreeBSD 13: I cannot reproduce #108962 bug, but the test failed when I forgot os.chflags(filename, 0). I fixed my PR and it now pass as well when os.chflags() doesn't fail.

[miss-islington]

Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

[miss-islington]

Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

[bedevere-bot]

GH-108967 is a backport of this pull request to the 3.12 branch.

[bedevere-bot]

GH-108968 is a backport of this pull request to the 3.11 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot s390x Fedora LTO + PGO 3.11 has failed when building commit 9dd28d2.

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/all/#builders/1023/builds/909) and take a look at the build logs.
4. Check if the failure is related to this commit (9dd28d2) 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/all/#builders/1023/builds/909

Failed tests:

• test_tools

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.11.edelsohn-fedora-z.lto-pgo/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
KeyError: '/psm_544675dc'


Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.11.edelsohn-fedora-z.lto-pgo/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
KeyError: '/psm_162f758e'


Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.11.edelsohn-fedora-z.lto-pgo/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
KeyError: '/psm_5e0c1d7a'