correct CC-BY link in doiRequestFile

doiRequestFile.yml

@@ -55,7 +55,7 @@ keywords:
 # Any rights information for this resource. Please provide both a license name and a link to the license.
 license:
   name: "CC-BY"
-  url: "https://creativecommons.org/licenses/by/2.0/"
+  url: "https://creativecommons.org/licenses/by/4.0/"
 
 ## Optional Fields