chore: Cleanup MANIFEST.in

[kesara]

Remove obsolete files and tests files from the MANIFEST.in

[rjsparks]

There's a package philosophy change being made here from "a pip install gives you a dev environment" to "if you want a dev environment you need to check things out from github" - are there documents to update?

[kesara]

There's a package philosophy change being made here from "a pip install gives you a dev environment" to "if you want a dev environment you need to check things out from github" - are there documents to update?

No, I think we should move away from MANIFEST.in and make the change to only use pyproject.toml.