Skip unreliable thread/process/socket tests in PySide6

[kristjanvalur]

Some internal error in PySide6 appears to cause crashes when certain combinations of tests are executed.
The crashes occur inside PySide6 at random times and random position in the test suite but always after having
run the eventloop tests.
This PR disables two classes of tests, which together seem to cause this issue.

Note that this does not fix the issue, only makes it rarer. Even with these disabled tests in place, I can still see the crash happen, only much more rarely. I guess the proper solution is to ask PySide6 maintainers to take a look.

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
src/qasync
_windows.py
tests
test_qeventloop.py					81
Project Total

This report was generated by python-coverage-comment-action

[hosaka]

In #154 you mention that pyside6>=6.8.0 causes these crashes. Should we keep these tests enabled for versions lower than 6.8.0?

[kristjanvalur]

I guess we could, but I'm not sure the test suite has any matrix tests for different PySide6 versions. For local development it might make sense.
I have also found during my work, that even disabling these tests does not completely remove the problem. There seems to be some instability in PySide6 regarding QThreads...

Not sure this should go in until we get some response from the QT team.
Alternatively, we could pin the CI to use 6.7.3 for testing, and make note of this for developers and users of qasync. Thread crashes in PySide should really not be our concern if we are certain we are doing everything right ourselves.

[kristjanvalur]

This is the wrong approach. Closing this in favor of #158