perf: Add GitHub Action to test benchmark on PRs

.github/workflows/benchmark.yml

@@ -0,0 +1,18 @@
+name: Benchmark
+
+on: [pull_request]
+
+jobs:
+  benchmark:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - uses: dart-lang/setup-dart@v1
+    - run: dart pub get
+
+    - uses: luanpotter/[email protected]
+      with:
+        paths: "."
+      env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}