This PR adds Ruby 3.1 to the CI matrix. As part of that process it:
Updates the version of ruby/setup-ruby to 1, so we pick up Ruby 3.1 (and future updates)
Conditionally adds the net-imap, net-pop, and net-smtp gems to the Gemfile for Ruby 3.1 and up (for which these gems are no longer automatically included).
This PR adds Ruby 3.1 to the CI matrix. As part of that process it:
ruby/setup-ruby
to 1, so we pick up Ruby 3.1 (and future updates)net-imap
,net-pop
, andnet-smtp
gems to the Gemfile for Ruby 3.1 and up (for which these gems are no longer automatically included).