buildkit/ExposeProtoCasing

Protocol names in EXPOSE instructions should be lowercase.

Description

Protocol names in the EXPOSE instruction should be specified in lowercase to maintain consistency and readability.

Bad:

EXPOSE 80/TcP

Good:

EXPOSE 80/tcp

The fix lowercases the protocol in EXPOSE port specs.

# Before
EXPOSE 8080/TCP

# After (with --fix)
EXPOSE 8080/tcp