Update tk-unreal Version and Name Template Filtering

- Update tk-unreal to v1.3.1
- Allow underscores on the {name} template for publish from Unreal

Author: ryanmayeda

core/templates.yml

@@ -39,7 +39,7 @@ keys:
         type: str
     name:
         type: str
-        filter_by: alphanumeric
+        filter_by: "^[A-Za-z0-9_]+$"
     iteration:
         type: int
     version:

env/includes/unreal/tk-unreal-location.yml

@@ -5,7 +5,7 @@
 
 
 tk-unreal.location:
-  version: v1.3.0
+  version: v1.3.1
   type: github_release
   organization: ue4plugins
   repository: tk-unreal