For #8196, fixes

Author: gplsteph

env/asset_step.yml

@@ -42,4 +42,6 @@ engines:
   tk-alias: '@alias.asset_step'
   tk-vred: '@vred.asset_step'
   tk-shotgun: '@shotgun.all'
-  tk-unreal: "@settings.tk-unreal.asset_step"
+  # Disabled for now since there is nothing specific
+  # for Asset step in tk-unreal at the moment.
+  # tk-unreal: "@settings.tk-unreal.asset_step"

env/includes/unreal/templates.yml

@@ -17,7 +17,7 @@ keys:
         type: str
     name:
         type: str
-        filter_by: alphanumeric
+        filter_by: '^[a-zA-Z0-9_-]+$'
     iteration:
         type: int
     version: