ci: bring back daily benchmarks (#777)

* ci: bring back daily benchmarks

* remove ugly spaces

.github/workflows/benchmarks.yml

+name: Benchmarks
+
+on:
+  schedule:
+    - cron: "0 0 * * *"
+
+jobs:
+  bench:
+    name: Run benchmarks daily
+    runs-on: ubuntu-latest
+    steps:
+
+      - name: Checkout Sources
+        uses: actions/checkout@v2.4.0
+
+      - name: Install Rust nightly toolchain
+        uses: actions-rs/toolchain@v1.0.7
+        with:
+          profile: minimal
+          toolchain: nightly
+          override: true
+
+      - name: Rust Cache
+        uses: Swatinem/rust-cache@v1.3.0
+
+      - name: Run benchmark
+        run: cargo bench -p jsonrpsee-benchmarks -- --output-format bencher | tee output.txt
+
+      - name: Store benchmark result
+        uses: rhysd/github-action-benchmark@v1
+        with:
+          tool: 'cargo'
+          output-file-path: output.txt
+          benchmark-data-dir-path: "bench/dev"
+          fail-on-alert: true
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          comment-on-alert: true
+          alert-comment-cc-users: '@niklasad1'
+          auto-push: true