CI: Enable clippy

To keep the codebase nice and clean we can run `clippy` as part of the
CI pipeline.

Enable `clippy` in a CI job.

Author: tcharding

.github/workflows/rust.yml

@@ -34,6 +34,22 @@ jobs:
           DO_DOCS: true
         run: ./contrib/test.sh
 
+  Clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - run: rustup component add clippy
+      - uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: --all-features -- -D warnings
+
   wasm:
     name: Stable - WebAssembly Build
     runs-on: ubuntu-latest