Updated tk-shotgun to use v0.8.1

Author: manneohrstrom

env/includes/engine_locations.yml

@@ -77,6 +77,6 @@ engines.tk-shell.location:
 engines.tk-shotgun.location:
   type: app_store
   name: tk-shotgun
-  version: v0.7.0
+  version: v0.8.1