Add dependabot groupings (#6598)

Add groupings for Go modules updates in dependabot. This will reduce the
number of PRs when projects update.
* `k8s.io/*`
* `go.etcd.io/etcd/*`

Signed-off-by: SuperQ <superq@gmail.com>

.github/dependabot.yml

@@ -5,6 +5,13 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+    groups:
+      k8s.io:
+        patterns:
+          - "k8s.io/*"
+      go.etcd.io:
+        patterns:
+          - "go.etcd.io/etcd/*"
 
   - package-ecosystem: "github-actions"
     directory: "/"