Revert "Pin skopeo to unbreak skopeo+bubblewrap"

This reverts commit 0d370a285b09bd28c5b1cdfc6b89d2997f67da5d.

Fixed by https://github.com/containers/skopeo/pull/653 so safe to
merge this once a new build appears in the PPA.

Change-Id: I858eee79d084016b6b71eec46a6118d78f68cafa

manifests/site.pp

@@ -773,10 +773,7 @@ node /^ze\d+\.open.*\.org$/ {
 
   apt::ppa { 'ppa:projectatomic/ppa': }
   package { 'skopeo':
-    # Pin skopeo back to 0.1.36-1~dev~ubuntu16.04.2~ppa14 which is before
-    # the code that changed the required capabilities, breaking the use of
-    # skopeo from inside of bubblewrap.
-    ensure  => '0.1.36-1~dev~ubuntu16.04.2~ppa14',
+    ensure  => present,
     require => [
       Apt::Ppa['ppa:projectatomic/ppa'],
       Class['apt::update'],