build: force clippy failing on warnings on github actions

Author: LastLeaf

.github/workflows/rust.yml

@@ -23,8 +23,8 @@ jobs:
     - name: Run tests
       run: cargo test --verbose
     - name: Clippy
-      run: cargo clippy
+      run: cargo clippy -- -D warnings
     - name: Clippy on no-default-features
-      run: cargo clippy --no-default-features
+      run: cargo clippy --no-default-features -- -D warnings
     - name: Clippy on all-features
-      run: cargo clippy --all-features
+      run: cargo clippy --all-features -- -D warnings