change web builder to stable

Author: tmthecoder

.github/workflows/main.yml

@@ -10,7 +10,7 @@ jobs:
         java-version: '12.x'
     - uses: subosito/flutter-action@v1
       with:
-        channel: 'beta' # Currently you have to use beta channel for Flutter web.
+        channel: 'stable'
     - name: Upgrades flutter
       run: flutter upgrade
     - name: Enable Web