Test beaker on Ruby 3.1

Gemfile

@@ -15,8 +15,13 @@ group :development do
   gem 'overcommit', '>= 0.39.1',  :require => false
 end
 
-group :system_tests do
-  gem 'voxpupuli-acceptance', '~> 3.0',  :require => false
+# only enable this gem group when we're on Ruby 3.1 or newer
+# beaker depends on Ruby 3.1 and bundler will poop itself when you're on an older Ruby (even when the gem group is ignored)
+if Gem::Requirement.create('>= 3.1.0').satisfied_by?(Gem::Version.new(RUBY_VERSION.dup))
+  group :system_tests do
+    gem 'beaker', git: 'https://github.com/bastelfreak/beaker', branch: 'ruby31'
+    gem 'voxpupuli-acceptance', '~> 3.0',  :require => false
+  end
 end
 
 group :release do