Fix a uniqueness violation for is_highest

When syncing content, we need to ignore the upstream status of is_highest.

[noissue]

(cherry picked from commit 8d7550b)

pulp_ansible/app/tasks/collections.py

@@ -1215,5 +1215,6 @@ def _post_save(self, batch):
                         continue
                     setattr(collection_version, attr_name, attr_value)
 
+                collection_version.is_highest = False
                 collection_version.save()
                 _update_highest_version(collection_version)