Run clippy in CI

Author: dtolnay

.github/workflows/ci.yml

@@ -24,6 +24,15 @@ jobs:
       - run: cargo check
       - run: cargo check --manifest-path binary/Cargo.toml
 
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    if: github.event_name != 'pull_request'
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@clippy
+      - run: cargo clippy -- -Dclippy::all -Dclippy::pedantic
+
   outdated:
     name: Outdated
     runs-on: ubuntu-latest