Add action to check benchmark

.github/workflows/bench.yml

@@ -0,0 +1,23 @@
+name: Benchmark (Linux)
+
+on: [push, pull_request]
+
+jobs:
+  check_benchmark:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@master
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          profile: minimal
+          override: true
+
+      - name: Check benchmark
+        uses: actions-rs/cargo@v1
+        with:
+          command: bench
+          args: --package=actix-service