Use rbenv-each to run a command for every installed Ruby version

The linked rbenv Show archive.org snapshot plugin rbenv-each Show archive.org snapshot is very helpful to keep QoL gems up to date that are not part of the Gemfile.

For example, you can bump the geordi version for all your rubies with the following command:

rbenv each gem update geordi

Another useful example would be to bulk-update bundler or rubygems.

Note that rbenv-each hasn't been updated since 2018, but it is fully functional for me.