lightly gem issues with Ruby 2.7

As you can see on

https://github.com/metanorma/metanorma-cli/actions/runs/5052752207/jobs/9066717975

the lightly gem needs to be constrained to version 0.3.2 if it is running under Ruby 2.7; template processing jobs are otherwise failing to install.

ERROR:  Error installing metanorma-cli:
    The last version of lightly (>= 0) to support your Ruby & RubyGems was 0.3.3. Try installing it with `gem install lightly -v 0.3.3` and then running the current command again
    lightly requires Ruby version >= 3.0. The current ruby version is 2.7.8.225.

That means your gemspec for the impacted three gems, pubid-iso, pubid-ieee, pubid-bsi, need to include conditional code that looks like

  if RUBY_VERSION <= '2.7'
  spec.add_dependency "lightly", "~> 0.3.3"
  else
  spec.add_dependency "lightly", "~> 0.4.0"
  end

metanorma / pubid-iso

lightly gem issues with Ruby 2.7 #231