test: fix the tests on windows + ci: test windows using GitHub Actions

[aminya]

• This adds Windows to GitHub Actions. I have removed the Appveyor config file. You should stop its app in the repository settings.
• Fixes the tests on Windows by:
  • normalizing the usage files
  • using temp_dir

[aminya]

Thanks for the merge.

Please also stop the Appveyor app from the settings. If you don't have access, there is a hacky way to suppress the error.

# empty appveyor
build: off

branches:
  only:
  - non-existing

[jyn514]

Hmm, I thought I disabled the appveyor build, but I still see it running on https://github.com/holmgr/cargo-sweep/pull/80: https://ci.appveyor.com/project/holmgr/cargo-sweep/builds/45770497

I guess it's only cloning the repo and doing nothing else, which is harmless if a little silly.

[jyn514]

ah, I needed to set it not to run on any branches as well - now it's working :)

Thanks for the help!