Add CI for clippy

.github/workflows/build.yml

@@ -193,3 +193,39 @@ jobs:
       - name: Check formatting
         run: |
           ./admin/fmt -- --check
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+      - name: Install rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+          default: true
+          components: clippy
+      - uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: -p rustls -- -D warnings
+
+  clippy-nightly:
+    name: Clippy (Nightly)
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+      - name: Install rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          override: true
+          default: true
+          components: clippy
+      - uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: -p rustls