Add basic keyring sanity test (python)

[rocodes]

We should include a basic pure python test (no additional dependencies) in the keyring repo that just tests that if the package is installed, the keyring file is in place in /etc/pki, and the expected key is in the rpm database. That way we can install the package in a fedora vm in CI and run the one test file.

(Basically the tester steps from #4)