Unpins apt 1.8 dependency in fixtures.yml and spec_helper_acceptance.

.fixtures.yml

@@ -1,8 +1,6 @@
 fixtures:
   repositories:
-    apt: 
-      repo: "https://github.com/puppetlabs/puppetlabs-apt.git"
-      branch: "1.8.x"
+    apt: "https://github.com/puppetlabs/puppetlabs-apt.git"
     stdlib: "https://github.com/puppetlabs/puppetlabs-stdlib.git"
     firewall: "https://github.com/puppetlabs/puppetlabs-firewall.git"
     concat: "https://github.com/puppetlabs/puppetlabs-concat.git"

spec/spec_helper_acceptance.rb

@@ -92,7 +92,7 @@ RSpec.configure do |c|
       end
 
       on host, puppet('module','install','puppetlabs-stdlib'), { :acceptable_exit_codes => [0,1] }
-      on host, puppet('module','install','puppetlabs-apt', '--version', '1.8.0', '--force'), { :acceptable_exit_codes => [0,1] }
+      on host, puppet('module','install','puppetlabs-apt'), { :acceptable_exit_codes => [0,1] }
       on host, puppet('module','install','--force','puppetlabs-concat'), { :acceptable_exit_codes => [0,1] }
     end