Reverts to v0.5.2 of the tk-shotgun engine. QA showed a publish2

regression when launched via browser integration. This is the cause.

Author: Jeff Beeland

env/includes/common/engines.yml

@@ -63,6 +63,6 @@ common.engines.tk-shell.location:
 common.engines.tk-shotgun.location:
     type: app_store
     name: tk-shotgun
-    version: v0.5.3
+    version: v0.5.2