Gemfile: Add required mutex_m

warning: mutex_m was loaded from the standard library, but is not part of the default gems starting from Ruby 3.4.0.
You can add mutex_m to your Gemfile or gemspec to silence this warning."

This came from activesupport 7.0.

Author: olleolleolle

Gemfile

@@ -23,6 +23,7 @@ gem 'jquery-ui-rails'
 
 # Use Active Storage variant
 gem 'image_processing', '~> 1.2'
+gem "mutex_m"
 gem 'nokogiri'
 gem 'omniauth'
 gem 'omniauth-github'

Gemfile.lock

@@ -247,6 +247,7 @@ GEM
     minitest (5.25.5)
     msgpack (1.7.5)
     multi_xml (0.6.0)
+    mutex_m (0.3.0)
     net-http (0.4.1)
       uri
     net-imap (0.4.20)
@@ -538,6 +539,7 @@ DEPENDENCIES
   launchy
   letter_opener
   listen (~> 3.9)
+  mutex_m
   nokogiri
   omniauth
   omniauth-github