[Added] setup dart step to workflow

Author: iamvivekkaushik

.github/workflows/publish.yml

@@ -8,26 +8,4 @@ on:
 # Publish using the reusable workflow from dart-lang.
 jobs:
   publish:
-    runs-on: ubuntu-22.04
-    steps:
-      - name: Checkout App Repo
-        uses: actions/checkout@v3
-
-      - name: Setup Ruby
-        uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: '2.7.2'
-
-      - name: Update version in Pubspec
-        run: ruby update_version.rb
-
-      - name: Install Flutter & Build App Bundle
-        uses: subosito/flutter-action@v2
-        with:
-          channel: 'stable'
-
-      - name: Install Flutter Packages
-        run: flutter pub get
-
-      - name: Publish to pub.dev
-        run: flutter pub pub publish -f
+    uses: dart-lang/setup-dart/.github/workflows/publish.yml@v1