fix pytest_report_header args for pytest 8.1.0

[antonsteenvoorden]

pytest-spark breaks as of pytest 8.1.0 As described in https://docs.pytest.org/en/7.1.x/reference/reference.html#pytest.hookspec.pytest_report_header

Changed in version 7.0.0: The start_path parameter was added as a pathlib.Path equivalent of the startdir parameter. The startdir parameter has been deprecated.

Since the parameter is unused, we can use dynamic positional arguments and fix pytest-spark

[antonsteenvoorden]

Closing in favor of #25