Disable scala-steward action (#4248)

It does not trigger other actions somehow, so we don't get any feedback
if bumps are working. It's also redundant to the Scala Steward runs by
https://github.com/scala-steward.

Keep the `workflow_dispatch` setup nevertheless, to be able to run Scala
Steward in case the official service fails again, since we see more
error message when running it manually.

Pull request: #4248

.github/workflows/scala-steward.yml

@@ -1,6 +1,6 @@
 on:
-  schedule:
-    - cron: '0 0 * * *' # daily
+#  schedule:
+#    - cron: '0 0 * * *' # daily
   workflow_dispatch:
 
 name: Scala Steward