Update auto-update.yml

.github/workflows/auto-update.yml

@@ -4,8 +4,21 @@ on:
   schedule:
     - cron: '0 0 * * *'
 jobs:
+  delete-branch:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          ref: ${{ github.ref }}
+      - name: Delete Branch
+        uses: dawidd6/action-delete-branch@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          branches: 'bot/auto-update'
   create-branch:
     runs-on: ubuntu-latest
+    needs: delete-branch
     steps:
       - name: Checkout
         uses: actions/checkout@v2