Allow Ruby 3

[yahonda]

This commit addresses this conflict to support Ruby version 3.

% ruby -v
ruby 3.0.0dev (2020-08-31T09:51:59Z master 86737c509c) [x86_64-darwin20]
% bundle
Fetching gem metadata from https://rubygems.org/.........
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies...
Bundler found conflicting requirements for the Ruby version:
  In Gemfile:
    Ruby (= 3.0.0)

    listen was resolved to 3.2.1, which depends on
      Ruby (~> 2.2, >= 2.2.7)

Ruby (~> 2.2, >= 2.2.7), which is required by gem 'listen', is not available in the local ruby installation
%

Fix #489

Note

• rake spec is failing with Ruby 3, which also fails with Ruby2.7.1 then I do not think this is related to the Ruby version.

• Ruby on Rails master branch is running CI against the Ruby master branch, which needs this fix to address this conflict https://buildkite.com/rails/rails/builds/71363#56e7a57e-e0cd-4cbc-8dda-a9580061536b/2402-2407

[yahonda]

Thanks for merging. It would be appreciated if the new version of listen is released to address this Rails CI error.

https://buildkite.com/rails/rails/builds/71484#3a7c0304-50fe-4e2b-98fd-c108d508d262/2365-2374

[ioquatix]

I will work on it. Should we merge https://github.com/guard/listen/pull/482 first?

[yahonda]

I think yes.

[dentarg]

@ioquatix Sorry to bother you. I'm just curious, did you manage to work out a release plan with Colin for #482? Or can this fix be released separately? Thanks for maintaining what feels like every important gem in the ecosystem! 😅