Benchmark action specify repository (#2419)

Author: voidpumpkin

.github/workflows/benchmark.yml

@@ -53,6 +53,7 @@ jobs:
       - uses: actions/checkout@v2
         with:
           path: "./yew"
+          repository: ${{ github.event.pull_request.head.repo.full_name }} 
           ref: "${{ github.head_ref }}"
 
       - uses: actions/checkout@v2