Pytest 8 introduced breaking changes: make fixes to align with Pytest 8

[eleanorjboyd]

changelog for pytest 8: https://docs.pytest.org/en/latest/changelog.html
tests fail for repo because session.name of this change:
[session.name](https://docs.pytest.org/en/latest/reference/reference.html#pytest.Session.name) is now ""; previously it was the rootdir directory name. This matches [session.nodeid](https://docs.pytest.org/en/latest/reference/reference.html#pytest.nodes.Node.nodeid) which has always been "".

[eleanorjboyd]

other changes which caused breakage in our tests (not in the user experience tho)

#8976: Running pytest pkg/init.py now collects the pkg/init.py file (module) only. Previously, it collected the entire pkg package, including other test files in the directory, but excluding tests in the init.py file itself (unless python_files was changed to allow init.py file).

and

#7777: Files and directories are now collected in alphabetical order jointly, unless changed by a plugin. Previously, files were collected before directories. See below for an example.