change automerge policy

Signed-off-by: Christian Kotzbauer <christian.kotzbauer@gmail.com>

.github/workflows/automerge.yml

@@ -1,22 +1,7 @@
 name: Merge PRs
 on:
-  pull_request:
-    types:
-      - labeled
-      - unlabeled
-      - synchronize
-      - opened
-      - edited
-      - ready_for_review
-      - reopened
-      - unlocked
-  pull_request_review:
-    types:
-      - submitted
-  check_suite:
-    types:
-      - completed
-  status: {}
+  schedule:
+    - cron: "0 */6 * * *"
 jobs:
   automerge:
     runs-on: ubuntu-latest
@@ -26,5 +11,6 @@ jobs:
         env:
           GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
           MERGE_LABELS: "approved,!work-in-progress,!hold"
-          MERGE_METHOD: "rebase"
+          MERGE_METHOD: "squash"
           MERGE_DELETE_BRANCH: "true"
+          UPDATE_LABELS: "approved,!work-in-progress,!hold"