[Crate] Enforce formatting in CI (#46)

* [CI] Check formatting

* Format all files

.github/workflows/ci.yml

@@ -28,3 +28,10 @@ jobs:
         override: true
     - name: Run MSRV
       run: cargo build
+    - name: Install nightly
+      uses: actions-rs/toolchain@v1
+      with:
+        toolchain: nightly
+        components: rustfmt
+    - name: Run formatting check
+      run: cargo +nightly fmt --check --verbose