Add TruffleRuby in CI

[eregon]

No description provided.

[eregon]

reline tests pass on the release: https://github.com/ruby/reline/actions/runs/11393086264/job/31700631836?pr=768
but not on truffleruby-head: https://github.com/ruby/reline/actions/runs/11393086264/job/31700632323?pr=768

 /home/runner/.rubies/truffleruby-head/lib/mri/bundler/runtime.rb:304:in `check_for_activated_spec!': You have already activated io-console 0.6.0, but your Gemfile requires io-console 0.7.2. Since io-console is a default gem, you can either remove your dependency on it or try updating to a newer version of bundler that supports io-console as a default gem. (Gem::LoadError)
	from /home/runner/.rubies/truffleruby-head/lib/mri/bundler/runtime.rb:25:in `block in setup'
	from <internal:core> core/enumerable.rb:107:in `block in map'
	from /home/runner/.rubies/truffleruby-head/lib/mri/bundler/spec_set.rb:165:in `each'
	from /home/runner/.rubies/truffleruby-head/lib/mri/bundler/spec_set.rb:165:in `each'
	from <internal:core> core/enumerable.rb:108:in `map'
	from /home/runner/.rubies/truffleruby-head/lib/mri/bundler/runtime.rb:24:in `setup'
	from /home/runner/.rubies/truffleruby-head/lib/mri/bundler.rb:162:in `setup'
	from /home/runner/.rubies/truffleruby-head/lib/mri/bundler/setup.rb:23:in `block in <top (required)>'
	from /home/runner/.rubies/truffleruby-head/lib/mri/bundler/ui/shell.rb:159:in `with_level'
	from /home/runner/.rubies/truffleruby-head/lib/mri/bundler/ui/shell.rb:111:in `silence'
	from /home/runner/.rubies/truffleruby-head/lib/mri/bundler/setup.rb:23:in `<top (required)>'
	from <internal:core> core/kernel.rb:255:in `require'

I can repro the same locally, @andrykonchin could you look into that?

[eregon]

The irb truffleruby job https://github.com/ruby/reline/actions/runs/11393086264/job/31700627032?pr=768 is very slow because it does gem rdoc --all --ri --no-rdoc (added in #572).
I think if possible it's worth to skip that on TruffleRuby.

[eregon]

With these changes the added jobs all pass, so I think it is worth merging as it is.