Remove mutex_m gem.

Author: ppostma

Gemfile.lock

@@ -40,7 +40,6 @@ GEM
     language_server-protocol (3.17.0.3)
     logger (1.6.1)
     minitest (5.25.1)
-    mutex_m (0.3.0)
     parallel (1.26.3)
     parser (3.3.6.0)
       ast (~> 2.4.1)
@@ -96,7 +95,6 @@ PLATFORMS
 DEPENDENCIES
   activerecord (~> 8.0.0)
   bundler (>= 1.12)
-  mutex_m
   rake (~> 13.0)
   rspec (~> 3.13.0)
   rubocop (~> 1.68.0)

smart_paginate.gemspec

@@ -25,7 +25,6 @@ Gem::Specification.new do |spec|
   spec.required_ruby_version = '>= 2.7.0'
 
   spec.add_development_dependency 'bundler', '>= 1.12'
-  spec.add_development_dependency 'mutex_m'
   spec.add_development_dependency 'rake', '~> 13.0'
   spec.add_development_dependency 'rspec', '~> 3.13.0'
   spec.add_development_dependency 'rubocop', '~> 1.68.0'