.fixtures.yml: Cleanup Puppet 5 leftovers

The core modules are a requirements for unit testing with Puppet 6 and
newer. This module doesn't support Puppet 5 anymore, so it can be
removed (we did the same at Vox Pupuli).

Author: bastelfreak

.fixtures.yml

@@ -1,18 +1,12 @@
 fixtures:
   repositories:
     apt: "https://github.com/puppetlabs/puppetlabs-apt.git"
-    augeas_core:
-      repo: "https://github.com/puppetlabs/puppetlabs-augeas_core.git"
-      puppet_version: ">= 6.0.0"
+    augeas_core: "https://github.com/puppetlabs/puppetlabs-augeas_core.git"
     concat: "https://github.com/puppetlabs/puppetlabs-concat.git"
     cron_core: "https://github.com/puppetlabs/puppetlabs-cron_core.git"
     facts: 'https://github.com/puppetlabs/puppetlabs-facts.git'
     firewall: "https://github.com/puppetlabs/puppetlabs-firewall.git"
     provision: "https://github.com/puppetlabs/provision.git"
     puppet_agent: 'https://github.com/puppetlabs/puppetlabs-puppet_agent.git'
     stdlib: "https://github.com/puppetlabs/puppetlabs-stdlib.git"
-    yumrepo_core: 
-      repo: "https://github.com/puppetlabs/puppetlabs-yumrepo_core.git"
-      puppet_version: ">= 6.0.0"
-  symlinks:
-    postgresql: "#{source_dir}"
+    yumrepo_core: "https://github.com/puppetlabs/puppetlabs-yumrepo_core.git"