CLN remove trailing whitespace in changelog

Author: pierreglaser

CHANGES.md

@@ -4,7 +4,7 @@
 - `cloudpickle`'s pickle.Pickler subclass (currently defined as
   `cloudpickle.cloudpickle_fast.CloudPickler`) can and should now be accessed
   as `cloudpickle.Pickler`. This is the only officially supported way of
-  accessing it. 
+  accessing it.
   ([issue #366](https://github.com/cloudpipe/cloudpickle/issues/366))