Why?
Please add reasons why this is changed not just that it's changed, that's plain to see from the code that there's a change.

@cpuguy83 why would we want to keep an older version ?

Bumping the go.mod means everyone who compiles it has to bump the go version.
What would you not support a still in-support go version?

Anyway, the point is not to say "you shouldn't have done this" but "what's the reason for the decision?".

everyone who compiles it has to bump the go version

obviously! But if you exclude a few Linux distribution maintainers who have to compile on their own, the many others just consume Docker Compose as a pre-built binary and aren't affected.

what's the reason for the decision?

because we want to rely on latest available and can benefits potential optimizations or new constructs it offers. We don't wait to see a coding opportunity to bump version.