Add cargo fmt to github actions

.github/workflows/rust.yml

@@ -15,12 +15,14 @@ jobs:
     - uses: actions/checkout@v2
     - name: Prepare
       run: sudo apt-get install -qy libsasl2-dev
-      
+
     - uses: actions-rs/clippy-check@v1
       with:
         token: ${{ secrets.GITHUB_TOKEN }}
-        args: --all-features  
+        args: --all-features
 
+    - name: Run cargo fmt
+      run: cargo fmt --all -- --check
     - name: Build
       run: cargo build --verbose
     - name: Run tests