Include golang 1.20.7 in the e2e gdk image

What does this MR do and why?

As noted in &11186 (closed) go 1.20.7 adds a limit to the maximum RSA key size. This adds go 1.20.7 as an alternative to 1.20.5 so that builds that specify 1.20 aren't immediately upgraded. This will let us run the e2e tests (which include some TLS tests) without causing unexpected failures.

Checklist

• (If applicable) Add patches if required for upgrading Ruby version in https://gitlab.com/gitlab-org/gitlab-build-images/-/tree/master/patches/ruby.