`launch_pytest` not building with pytest >= 8.4

[claraberendsen]

Description

Testing on Resolute with pytest version 9.0.2 is failing with a build regression on launch_pytest with error:

E AttributeError: 'FixtureFunctionDefinition' object has no attribute '_pytestfixturefunction'. Did you mean: '_fixture_function'? 

Reference:

Since version 8.4.0 of pytest the fixture representation has changed from a function to a class. See https://docs.pytest.org/en/stable/changelog.html#pytest-8-4-0-2025-06-02 in particular

#11525: Fixtures are now clearly represented in the output as a “fixture object”, not as a normal function as before, making it easy for beginners to catch mistakes such as referencing a fixture declared in the same module but not requested in the test function.

With this change _pytestfixturefunction no longer exists causing the error.