chore: update permissions

Author: TomAFrench

.github/workflows/benchmark.yml

@@ -10,6 +10,9 @@ jobs:
   test:
     name: Benchmark library
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
     steps:
       - name: Checkout sources
         uses: actions/checkout@v4