Consider getting rid of Bundler's cache before saving the gems to the CI cache
Thanks to a RailsConf talk, I discovered that Bundler is having its own cache under vendor/ruby/2.7.0/cache
(when gems are installed under vendor
as we do).
We probably don't need this Bundler cache as we refresh our own cache of gems every two hours.
From a quick check, it seems this cache accounts for 91MB: https://gitlab.com/gitlab-org/gitlab/-/jobs/1172621220#L65.