Bump PSH minimum version to 2.9.0

Author: DavidS

config/dependencies.yml

@@ -29,7 +29,7 @@ dependencies:
         - gem: puppet-syntax
           version: ['>= 2.4.1', '< 3.0.0']
         - gem: puppetlabs_spec_helper
-          version: ['>= 2.8.0', '< 3.0.0']
+          version: ['>= 2.9.0', '< 3.0.0']
         - gem: rainbow
           version: '~> 2.0'
         - gem: rspec-puppet