Python 3.13 compatibility

It seems that with new Python 3.13 alpha 3.13.0a5 (note with previous alpha this seemed not to happen as besides the small fix of #5035 it worked fine) tests fail very early:


+ cd robotframework-7.0
+ /usr/bin/python3 utest/run.py
Traceback (most recent call last):
  File "/builddir/build/BUILD/robotframework-7.0/utest/run.py", line 99, in <module>
    tests = get_tests(args.directory)
            ~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/builddir/build/BUILD/robotframework-7.0/utest/run.py", line 56, in get_tests
    tests.extend(get_tests(fullname))
                 ~~~~~~~~~^^^^^^^^^^
  File "/builddir/build/BUILD/robotframework-7.0/utest/run.py", line 66, in get_tests
    module = __import__(modname)
             ~~~~~~~~~~^^^^^^^^^
  File "/builddir/build/BUILD/robotframework-7.0/utest/parsing/test_model.py", line 41, in <module>
    EXPECTED = File(sections=[
               ~~~~^^^^^^^^^^^
        ImplicitCommentSection(
        ^^^^^^^^^^^^^^^^^^^^^^^
    ...<86 lines>...
        )
        ^
    ])
    ^^
  File "/builddir/build/BUILD/robotframework-7.0/utest/../src/robot/parsing/model/blocks.py", line 72, in __init__
    super().__init__()
    ~~~~~~~~~~~~~~~~^^
SystemError: <method-wrapper '__init__' of File object at 0x7fc54cea0190> returned NULL without setting an exception

I tried to investigate a bit but sincerely got a bit lost in the flow of inheritance and what that super call should achieve. I know there is still some time for Python 3.13, but still reporting if it may give you an early warning.

If you have any proposal on a fix and need help to retest please just let me know!