Updated tk-nuke to v0.15.8

Release notes: https://github.com/shotgunsoftware/tk-nuke/releases/tag/v0.15.8

Author: toolkitty

env/includes/common/engines.yml

@@ -26,7 +26,7 @@ common.engines.tk-maya.location:
 common.engines.tk-nuke.location:
   type: app_store
   name: tk-nuke
-  version: v0.15.7
+  version: v0.15.8
 common.engines.tk-photoshopcc.location:
   type: app_store
   name: tk-photoshopcc