Group minor dependabot updates

The goal of this patch is to make the monthly
reviewing of dependency prs more efficient.
It causes dependabot to group all minor and
patch dependency updates into a single pull
request. The reasoning is that minor updates
are highly unlikely to cause our app to break or
change and thus time can be saved by testing
them all at once instead of individually.

Inspired by Opencast studio:
https://github.com/elan-ev/opencast-studio/blob/master/.github/dependabot.yml

.github/dependabot.yml

@@ -17,3 +17,8 @@ updates:
     open-pull-requests-limit: 15
     labels:
       - type:dependencies
+    groups:
+      minor-and-patch:
+        update-types:
+          - minor
+          - patch