Fixes pytests tests when using Python 3.7 (PyO3#5095)

* Disable positional only test in Python 3.7

* Update pytests/tests/test_pyfunctions.py

Co-authored-by: Nathan Goldbaum <[email protected]>

* fix ruff

---------

Co-authored-by: Nathan Goldbaum <[email protected]>

Author: Tpt

pytests/tests/test_pyfunctions.py

@@ -87,7 +87,10 @@ def test_args_kwargs_rs(benchmark):
     assert rust == py
 
 
-def positional_only_py(a, /, b):
+# TODO: the second argument should be positional-only
+# but can't be without breaking tests on Python 3.7.
+# See gh-5095.
+def positional_only_py(a, b):
     return a, b