Add GitHub actions CI

.github/workflows/flutter.yaml

@@ -0,0 +1,27 @@
+name: CI
+
+on:
+  push:
+    branches: [master, develop]
+  pull_request:
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/cache@v3
+        with:
+          path: |
+            ~/.gradle/wrapper
+            /opt/hostedtoolcache/flutter
+          key: ${{ runner.OS }}-flutter-install-cache
+      - uses: subosito/flutter-action@v2
+        with:
+          channel: 'stable'
+      - name: Project preparation
+        run: flutter pub get
+      - name: Flutter format
+        run: flutter format -o none --set-exit-if-changed .
+      - name: Flutter analyze
+        run: flutter analyze