updated CI

This adds a build run and also triggers a run on every push, not just
PRs, so that we can display badges for the main branch.

Author: pazz

.github/workflows/clippy.yml

@@ -0,0 +1,23 @@
+name: Rust CI 
+on: [push, pull_request] 
+
+jobs: 
+  build: 
+    runs-on: ubuntu-latest 
+
+    steps: 
+    - uses: actions/checkout@v2 
+    - name: Set up Rust 
+      uses: actions-rs/toolchain@v1 
+      with: 
+        toolchain: stable 
+        profile: minimal 
+        override: true 
+    - name: Cache Cargo dependencies
+      uses: Swatinem/rust-cache@v2
+    - name: Build 
+      run: cargo build --verbose 
+    - name: Run tests 
+      run: cargo test --all-features --verbose
+    - name: Run linter
+      run: cargo clippy -- -D warnings