fix(error with repository): removed a field that is not being used

this causes an exception when getting releases

Issue: https://coreosdev.atlassian.net/browse/QUAY-753

- [ ] It works!
- [ ] Comments provide sufficient explanations for the next contributor
- [ ] Tests cover changes and corner cases
- [ ] Follows Quay syntax patterns and format

endpoints/api/repository_models_interface.py

@@ -131,11 +131,10 @@ class Channel(namedtuple('Channel', ['name', 'linked_tag_name', 'linked_tag_life
 
 
 class Release(
-    namedtuple('Channel', ['name', 'released', 'lifetime_start', 'releases_channels_map'])):
+    namedtuple('Channel', ['name', 'lifetime_start', 'releases_channels_map'])):
   """
   Repository a single quay repository
   :type name: string
-  :type released: string
   :type last_modified: string
   :type releases_channels_map: {string -> string}
   """

endpoints/api/repository_models_pre_oci.py

@@ -149,7 +149,7 @@ class PreOCIModel(RepositoryDataInterface):
       releases_channels_map = defaultdict(list)
       return ApplicationRepository(
         base, [create_channel(channel, releases_channels_map) for channel in channels], [
-          Release(release.name, release.released, release.lifetime_start, releases_channels_map)
+          Release(release.name, release.lifetime_start, releases_channels_map)
           for release in releases
         ])