Use latest spring-merge-dependabot-pr.yml

The `autoMergeSnapshots` is a new convenient input

**Auto-cherry-pick to `3.1.x`**

Author: artembilan

.github/workflows/merge-dependabot-pr.yml

@@ -12,6 +12,7 @@ jobs:
   merge-dependabot-pr:
     permissions: write-all
 
-    uses: spring-io/spring-github-workflows/.github/workflows/spring-merge-dependabot-pr.yml@v3
+    uses: spring-io/spring-github-workflows/.github/workflows/spring-merge-dependabot-pr.yml@main
     with:
-      mergeArguments: --auto --squash
+      mergeArguments: --auto --squash
+      autoMergeSnapshots: true