Add a benchmark github workflow

.github/workflows/benchmarks.yml

@@ -0,0 +1,15 @@
+---
+on: [pull_request]
+
+name: Benchmark pull requests
+
+jobs:
+  runBenchmark:
+    name: run benchmark
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - name: run benchmark
+        uses: matchai/criterion-compare-action@master
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}