Should Package@swift-5.4.swift and 5.5 be removed?

[adam-fowler]

It appears Swift 5.7 is required now. If so the 5.4 and 5.5 Package.swift should probably be removed.

Similarly the docker-compose.al2.56.yaml file could be removed

[sebsto]

Just created #49
I let you review and approve if you have no feedback