Fix docs generation broken with switch to build with uv

[blairconrad]

FakeItEasy/FakeItEasy#2042 moved the mkdocs config files into the docs directory, breaking our ability to generate docs from this package, since we no longer have a requirements.txt file.
FakeItEasy/FakeItEasy#2044 made things a little worse by moving the configuration files.
And we never made either of these changes to FakeItEasy.Analyzers.

I propose to

• fix the mkdocs configuration in FakeItEasy (Fix docs build location FakeItEasy#2065)
  • modernize the uv, python, and mike dependencies in FakeItEasy while I'm there
• convert this project to use uv and to be able to build the FakeItEasy docs
• create an issue to convert the FakeItEasy.Analyzers docs-building to match FakeItEasy (I'm not committing to fixing that now, since we may never build the docs again; I think it's enough to note that the docs can't be built and fix as we feel like it)

[blairconrad]

@thomaslevesque, if this makes sense, I'll send a PR for the FakeItEasy changes within the next couple of days today. The change to this repo should come pretty quickly thereafter.