fix checkout action

.github/workflows/bench-reports.yml

@@ -18,7 +18,10 @@ jobs:
       contents: read
       pull-requests: write
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          ref: main
       - name: run benching script
         run: ./bench.sh
       - name: preserve bench artifacts