(gh-19) Bump to Beaker 6 for acceptance

The Beaker 5 provision step preps .ssh/environment but leaves
/etc/environment as is. The .ssh/environment is later configured by the
acceptance/suites/pre_suite/openvox/configure_type_defaults.rb to
include a PATH that has /opt/puppetlabs/bin. However On Ubuntu20+,
/etc/environment (which has a PATH without /opt/puppetlabs/bin) seems to
get sourced after .ssh/environment, causing test that attempt to find
puppet tools to fail. (18.04 works fine, though /etc/environment still
has a PATH without /opt/puppetlabs, so presumably it's not sourced or
source order is different?).

At any rate, Beaker 6 explicitly clears out /etc/environment in the
beaker provision step, allowing ubuntu 20+ to work again.

:/

Author: jpartlow

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")