dependabot: Group patch updates

This only groups patch level updates: this might not do that much
considering the inconsistent version numbers in the relevant
ecosystems... We could add "minor" updates too but then there's
more chance of broken dependebot group updates

Signed-off-by: Jussi Kukkonen <jkukkonen@google.com>

Author: jku

.github/dependabot.yml

@@ -18,11 +18,23 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+    groups:
+      go-patch-updates:
+        update-types:
+          - "patch"
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: "weekly"
+    groups:
+      actions-patch-updates:
+        update-types:
+          - "patch"
   - package-ecosystem: "docker"
     directory: "/"
     schedule:
       interval: "weekly"
+    groups:
+      docker-patch-updates:
+        update-types:
+          - "patch"