CI: Fixate concurrent-ruby for Rails 7.0 support

The fixes in Solidus are not available everywhere yet.

Author: tvdeyen

Gemfile

@@ -27,3 +27,7 @@ end
 # Use a local Gemfile to include development dependencies that might not be
 # relevant for the project or for other contributors, e.g.: `gem 'pry-debug'`.
 eval_gemfile 'Gemfile-local' if File.exist? 'Gemfile-local'
+
+if rails_version == "~> 7.0"
+  gem 'concurrent-ruby', '< 1.3.5'
+end

lib/solidus_dev_support/templates/extension/Gemfile.tt

@@ -29,6 +29,10 @@ else
   gem 'sqlite3', '~> 1.4'
 end
 
+if rails_version == '~> 7.0'
+  gem 'concurrent-ruby', '< 1.3.5'
+end
+
 # While we still support Ruby < 3 we need to workaround a limitation in
 # the 'async' gem that relies on the latest ruby, since RubyGems doesn't
 # resolve gems based on the required ruby version.