Update Ruby 3 to 3.0.2

This bumps the Ruby 3 images to the latest patch release 3.0.2.

It will unblock labkit-ruby!68

I wasn't sure if I needed to change all the references to custom build images such as ruby-3.0.0.patched-golang-1.14-git-2.31-lfs-2.9-chrome-89-node-14.15-yarn-1.22-postgresql-11-graphicsmagick-1.3.36 test: *test_custom but it looks like we match just on the minor version:

3.0|3.0.*)
            RUBY_VERSION="3.0.2"
            RUBY_DOWNLOAD_SHA256="5085dee0ad9f06996a8acec7ebea4a8735e6fac22f22e2d98c3f2bc3bef7e6f1"
            ;;

so should be OK?