Replace Appveyor PR pipeline with Github Actions

[Stedoss]

Super simple pipeline to hopefully replace the older one.

Python 3.9 was picked because it worked, but we can pick another or do a matrix (eg. 3.9, 3.10, 3.11).

Have also updated the tests to reflect the current state of the leaderboards for the tests, but they can be changed/removed if we want.

Requirements for merge:

• API Key needs to be added to the repo actions secrets.

[tybug]

I've added OSU_API_KEY to this repo's secrets. But I just read this, which might mean this idea is dead in the water....emphasis mine https://github.com/circleguard/circlecore/settings/secrets/actions

Anyone with collaborator access to this repository can use these secrets and variables for actions. They are not passed to workflows that are triggered by a pull request from a fork.

this is a huge test improvement regardless though, thanks! appveyor definitely needed to go.