Fix compatibility with pytest-run-parallel and add free-threaded CI jobs

[astrofrog]

Without this fix, we can't run tests with pytest-run-parallel if those tests rely on pytest-arraydiff (which is used e.g. in reproject):

hook_name = 'pytest_runtest_call', hook_impl = <HookImpl plugin_name='140326316292304', plugin=<pytest_arraydiff.plugin.ArrayComparison object at 0x7fa0443c38d0>>
e = AttributeError("'NoneType' object has no attribute 'writeto'")

    def _warn_teardown_exception(
        hook_name: str, hook_impl: HookImpl, e: BaseException
    ) -> None:
        msg = "A plugin raised an exception during an old-style hookwrapper teardown.\n"
        msg += f"Plugin: {hook_impl.plugin_name}, Hook: {hook_name}\n"
        msg += f"{type(e).__name__}: {e}\n"
        msg += "For more information see https://pluggy.readthedocs.io/en/stable/api_reference.html#pluggy.PluggyTeardownRaisedWarning"  # noqa: E501
>       warnings.warn(PluggyTeardownRaisedWarning(msg), stacklevel=6)
E       pluggy.PluggyTeardownRaisedWarning: A plugin raised an exception during an old-style hookwrapper teardown.
E       Plugin: 140326316292304, Hook: pytest_runtest_call
E       AttributeError: 'NoneType' object has no attribute 'writeto'
E       For more information see https://pluggy.readthedocs.io/en/stable/api_reference.html#pluggy.PluggyTeardownRaisedWarning

../../../python/dev/lib/python3.11/site-packages/pluggy/_callers.py:73: PluggyTeardownRaisedWarning

The fix here ensures we don't wrap the tests multiple times, and make sure we always pass output values through.

(Note: I pushed this to an upstream branch by mistake as this repo used to be under my user - will fix it for future)

[neutrinoceros]

I'd suggest going straight to 314t here:

• 3.13t was always experimental
• cibuildwheel is currently sunsetting it so it seems unlikely that tables will ever support it

[neutrinoceros]

shouldn't this use the builtin pytester fixture instead ? https://docs.pytest.org/en/stable/reference/reference.html#std-fixture-pytester

It does require pytest>=6.2, which is very reasonable now IMO (6.2 came out in 2020)

[neutrinoceros]

I suggest using the tmp_path builtin fixture here

Suggested change

	tmpdir = tempfile.mkdtemp()
	test_file = os.path.join(tmpdir, 'test.py')
	with open(test_file, 'w') as f:
	f.write(TEST_PARALLEL)
	gen_dir = os.path.join(tmpdir, 'reference')
	test_file = tmp_path / 'test.py'
	test_file.write_test(TEST_PARALLEL)
	gen_dir = tmp_path / 'reference'

[neutrinoceros]

I don't think this additional comment is particularly helpful here; it'd be much more fitting in tox.ini

[neutrinoceros]

Aligning the phrasing with the way configuration is written

Suggested change

	# which CI does not install. Skip the HDF5 extras on free-threaded
	# envs.
	# which CI does not install. Only run these test on GIL-enabled builds.

[neutrinoceros]

isn't this implementation now exactly equivalent to the default ?