Lock concurrent-ruby to < 1.3.5 on Rails < 7.2

See https://stackoverflow.com/questions/79360526/uninitialized-constant-activesupportloggerthreadsafelevellogger-nameerror

Author: mamhoff

Gemfile

@@ -3,16 +3,16 @@
 source 'https://rubygems.org'
 git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
-branch = ENV.fetch('SOLIDUS_BRANCH', 'main')
-gem 'solidus', github: 'solidusio/solidus', branch: branch
+solidus_branch = ENV.fetch('SOLIDUS_BRANCH', 'main')
+gem 'solidus', github: 'solidusio/solidus', branch: solidus_branch
 
 # The solidus_frontend gem has been pulled out since v3.2
-if branch >= 'v3.2'
+if solidus_branch >= 'v3.2'
   gem 'solidus_frontend'
-elsif branch == 'main'
+elsif solidus_branch == 'main'
   gem 'solidus_frontend', github: 'solidusio/solidus_frontend'
 else
-  gem 'solidus_frontend', github: 'solidusio/solidus', branch: branch
+  gem 'solidus_frontend', github: 'solidusio/solidus', branch: solidus_branch
 end
 
 # Needed to help Bundler figure out how to resolve dependencies,
@@ -35,6 +35,10 @@ end
 # Temporarily link solidus_support with Flickwerk support
 gem "solidus_support", github: "mamhoff/solidus_support", branch: "re-enable-flickwerk"
 
+if ["v4.1", "v4.2"].include?(solidus_branch)
+  gem "concurrent-ruby", "< 1.3.5"
+end
+
 gemspec
 
 # Use a local Gemfile to include development dependencies that might not be