Upgrade cross repo tests to ruby 3.1

[kbrock]

cross repo tests for ui-classic are failing for me.

Locally, running ui-classic tests with ruby 3.0 are failing for me:

Before

cd manageiq-ui-classic
git checkout master
chruby 3.0
bundle exec rake

An error occurred while loading spec_helper.
Failure/Error: Vmdb::Application.initialize!

RuntimeError:
  Application has been already initialized.
# ruby/3.0.6/gems/railties-6.1.7.7/lib/rails/application.rb:390:in `initialize!'
# ruby/3.0.6/gems/railties-6.1.7.7/lib/rails/railtie.rb:207:in `public_send'
# ruby/3.0.6/gems/railties-6.1.7.7/lib/rails/railtie.rb:207:in `method_missing'
# ./spec/manageiq/config/environment.rb:5:in `<top (required)>'
# ruby/3.0.6/gems/bootsnap-1.18.3/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
# ruby/3.0.6/gems/zeitwerk-2.6.13/lib/zeitwerk/kernel.rb:34:in `require'
# ruby/3.0.6/gems/bootsnap-1.18.3/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
# ruby/3.0.6/gems/zeitwerk-2.6.13/lib/zeitwerk/kernel.rb:34:in `require'

After

cd manageiq-ui-classic
chruby 3.1
bundle exec rake
# It works

[agrare]

No issue with starting to default to 3.1 but I'd like to add an option for the user to specify a ruby version or set of ruby versions similar to how we have the --test-suite option

[Fryguy]

LGTM - @agrare I think let's merge this, then we can do the change you're suggesting separately in the bot