ci: add pr check

.github/workflows/pr-check.yaml

@@ -0,0 +1,30 @@
+name: PR check
+
+on:
+  pull_request:
+    branches:
+      - master
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: subosito/flutter-action@v2
+        with:
+          channel: 'stable'
+
+      - name: Check
+        run: |
+          flutter pub get
+          dart fix
+          dart format .
+          git diff --exit-code
+          if [ $? -eq 0 ]; then
+            echo "No formatting changes detected"
+          else
+            echo "Formatting changes detected. Run `make format` to fix it."
+            exit 1
+          fi