[actions] Fix automerge actions don't work issue. (sonic-net#11671)

Author: liushilongbuaa

.github/workflows/automerge.yml

@@ -15,7 +15,7 @@ jobs:
     - name: automerge
       uses: 'pascalgn/[email protected]'
       env:
-        GITHUB_TOKEN: '${{ secrets.GITHUB_TOKEN }}'
+        GITHUB_TOKEN: '${{ secrets.TOKEN }}'
         MERGE_LABELS: 'automerge'
         MERGE_METHOD: 'squash'
         MERGE_FILTER_AUTHOR: 'mssonicbld'