ci: add PR code formatting check

Add a CI pipeline to validate code formatting on Pull Requests.

Signed-off-by: Renato Westphal <[email protected]>

.github/workflows/ci.yaml

@@ -1,10 +1,6 @@
 name: CI
 
-on:
-  push:
-    branches: [ master ]
-  pull_request:
-    branches: [ master ]
+on: [push, pull_request]
 
 env:
   CARGO_TERM_COLOR: always
@@ -24,6 +20,10 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - uses: dtolnay/rust-toolchain@nightly
+      - uses: mbrobbel/rustfmt-check@master
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          mode: review
       - name: Generate test result and coverage report
         run: |
           cargo install cargo2junit grcov;
@@ -41,7 +41,7 @@ jobs:
           files: ./lcov.info
           fail_ci_if_error: true
 
-  push-store-image:
+  push-image:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3