Add rubygems 3.3.20, remove rubygems 3.3.19
Add rubygems 3.3.20, remove rubygems 3.3.19

for stack(s) cflinuxfs3 [#182952392]

cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack,cloudfoundry/ruby-buildpack