Drop test dependency on path package

[Avasam]

Summary of changes

As far as I can tell, pathlib+jaraco.path should be sufficient, and it's only used in tests. There may be issues with vendored deps, let's see what the CI says.

Closes

Pull Request Checklist

• Changes have tests (these are the test changes)
• News fragment added in newsfragments/. (no public changes, tests only)
  (See documentation for details)

[Avasam]

After making this PR for something that looked like an unnecessary extra dependency. I went and looked at what exactly is path (my first assumption being that it was some compat module from before pathlib). Especially https://pypi.org/project/path#advantages .
It makes me curious about the separation between jaraco/path and jaraco/jaraco.path.

I also noticed that path.Path.parts and pathlib.Path.parts are incompatible (one's a method, the other's a property)