Use Ruby 3.4 in the latest version of CI

This PR uses Ruby 3.4 in the latest version of CI.

This PR suppresses the following warnings:

## Cucumber

```console
Run BUNDLE_GEMFILE=gemfiles/cucumber1_3.gemfile vendor/bats/bin/bats test/cucumber.bats
(snip)

# /opt/hostedtoolcache/Ruby/3.4.1/x64/lib/ruby/gems/3.4.0/gems/cucumber-1.3.20/lib/cucumber/cli/drb_client.rb:1:
warning: drb/drb was loaded from the standard library, but is not part of the default gems starting from Ruby 3.4.0.
# You can add drb to your Gemfile or gemspec to silence this warning.
```

https://github.com/tmm1/test-queue/actions/runs/12557591208/job/35010466650?pr=134

## Minitest

```console
Run BUNDLE_GEMFILE=gemfiles/minitest5.gemfile vendor/bats/bin/bats test/minitest5.bats
(snip)

# /opt/hostedtoolcache/Ruby/3.4.1/x64/lib/ruby/gems/3.4.0/gems/minitest-5.10.0/lib/minitest.rb:3:
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.
```

https://github.com/tmm1/test-queue/actions/runs/12557591208/job/35010466855?pr=134

.github/workflows/test.yml

@@ -18,8 +18,8 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu]
-        # Lowest and Latest version.
-        ruby: ['2.7', '3.3']
+        # Lowest and Latest versions.
+        ruby: ['2.7', '3.4']
         entry:
           - { name: cucumber1_3, bats: test/cucumber.bats }
           - { name: cucumber2_4, bats: test/cucumber.bats }

gemfiles/cucumber1_3.gemfile

@@ -5,6 +5,7 @@
 source 'https://rubygems.org'
 
 gem 'cucumber', '~> 1.3.10'
+gem 'drb'
 gem 'rake', '< 11.0'
 gem 'rspec', '>= 2.13', '< 4.0'
 

gemfiles/minitest5.gemfile

@@ -4,6 +4,7 @@
 
 source 'https://rubygems.org'
 
+gem 'mutex_m'
 gem 'minitest', '5.10.0'
 
 gemspec path: '../'