use year instead of complete date

copier.yaml

@@ -44,7 +44,7 @@ short_description:
   default: "the skeleton of a python lib with everything I like"
   help: "A short description of the project"
 
-creation_date:
+creation_year:
   type: str
   default: {% now 'utc', '%Y' %}
   help: "The creation date of your package, don't change unless it's a manual update"