(maint) Update to Beaker 6.x

Turned out the real pain was moving from 4.x -> 5.x and I needed at
least version 5.4 for Debian 12 support. Might as well move to latest
while we're updating dependencies.

Author: justinstoller

Gemfile

@@ -18,7 +18,7 @@ gem 'rake', :group => [:development, :test]
 
 group :test do
   gem 'rspec'
-  gem 'beaker', *location_for(ENV['BEAKER_VERSION'] || '~> 5.4')
+  gem 'beaker', *location_for(ENV['BEAKER_VERSION'] || '~> 6.0')
   gem "beaker-hostgenerator", *location_for(ENV['BEAKER_HOSTGENERATOR_VERSION'] || "~> 2.4")
   gem "beaker-abs", *location_for(ENV['BEAKER_ABS_VERSION'] || "~> 1.0")
   gem "beaker-vmpooler", *location_for(ENV['BEAKER_VMPOOLER_VERSION'] || "~> 1.3")