Make it easier to use the test suite

[jku]

Two options

1. Provide a GitHub Action that TUF implementations can use
2. Make releases to pypi, let TUF implementations handle the CI integration

Doing both might make sense, but the GH action might be most important?

GitHub Action

If this repo includes the github action, then that action does not actually need the pypi releases (as it can just install from the sources). The action should take at least the client-wrapper path as argument, and should then

• install test suite requireements
• install test suite
• run test suite with given client wrapper

PyPI releases

Releases in pypi would make using the test suite in CI is easy for the TUF implementations.

python-tuf release job might be useful: https://github.com/theupdateframework/python-tuf/blob/develop/.github/workflows/cd.yml

• release process is started on push to "v*" tag
• needs a "release" environment which should have required reviewers
• pypi project should use Trusted publishing https://github.com/marketplace/actions/pypi-publish#trusted-publishing

[jku]

I believe this is mostly already fixed or obsolete:

• an action exists now and seems to work fine
• if the action is the recommended way to use this test suite we don't need to do pypi releases