Full testing including S3 testing with min.io

[noamross]

This is a complex set up - we have two online services, (AWS) S3 and GitHub, and both git hashes and S3 version IDs are not predictable (they may be deterministic but integrate seeds and timestamps). S3 we can imitate with a local min.io server, but GH mocking will be tough, as we'd have to artificially generate mocks based on hashes generated in the example git repos. So it may make more sense to push the example repo to GitHub and test directly against it, or push up to test and then generate mocks from that each time.