Update main.yml

Author: hyouhyan

.github/workflows/main.yml

@@ -15,7 +15,7 @@ jobs:
         id: get_diff
         run: |
           git fetch origin
-          git rev-list --count main... > diff.txt
+          git rev-list --count main...dev > diff.txt
           echo "::set-output name=behind::$(cat diff.txt | cut -d' ' -f1)"
       - name: Notify Discord
         run: |