Updated tk-shell to v0.8.1

Release notes: https://github.com/shotgunsoftware/tk-shell/wiki/Release-Notes#v081

Author: Toolkitty

env/includes/common/engines.yml

@@ -87,7 +87,7 @@ common.engines.tk-desktop2.location:
 common.engines.tk-shell.location:
   type: app_store
   name: tk-shell
-  version: v0.8.0
+  version: v0.8.1
 
 # shotgun
 common.engines.tk-shotgun.location: