ci: setup GitHub Actions

Implements: #5

.github/workflows/github-action.yaml

@@ -0,0 +1,26 @@
+name: bloc_lint
+
+on:
+  pull_request:
+    branches: [ main ]
+  push:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          flutter-version: '3.24.1'
+          channel: 'stable'
+
+      - name: Get dependencies
+        run: flutter pub get
+
+      - name: Test lint rules
+        run: cd example && dart run custom_lint && cd ..