Define a name value for the size deltas report workflow

When a `name` value is not defined, the workflow is identified by its path, which is less friendly than a custom name.

Author: per1234

.github/workflows/report-size-deltas.yml

@@ -1,3 +1,5 @@
+name: Report Size Deltas
+
 on:
   schedule:
     - cron:  '*/5 * * * *'