Run clippy in CI

.github/workflows/rust.yml

@@ -22,3 +22,5 @@ jobs:
       run: cargo build --verbose
     - name: Run tests
       run: cargo test --verbose
+    - name: Clippy
+      run: cargo clippy

src/lib.rs

@@ -1,3 +1,4 @@
+#![deny(warnings)]
 #![allow(dead_code)]
 #![deny(unsafe_code)]