Update for pytest 7

[scottj97]

When using with pytest 7.0.0 I am seeing lots of deprecation warnings:

../../../build/python-venv/lib/python3.10/site-packages/_pytest/nodes.py:686: 511 warnings
../../../build/python-venv/lib/python3.10/site-packages/pytest_cram/__init__.py:55: 511 warnings
  The (fspath: py.path.local) argument to CramItem is deprecated. Please use the (path: pathlib.Path) argument instead.
  See https://docs.pytest.org/en/latest/deprecations.html#fspath-argument-for-node-constructors-replaced-with-pathlib-path

../../../build/python-venv/lib/python3.10/site-packages/_pytest/nodes.py:146: 146 warnings
  <class 'pytest_cram.CramItem'> is not using a cooperative constructor and only takes {'fspath', 'parent'}.
  See https://docs.pytest.org/en/stable/deprecations.html#constructors-of-custom-pytest-node-subclasses-should-take-kwargs for more details.

These go away when I revert back to pytest 6.2.5.