fix .env on dev

lib/main.dart

@@ -6,7 +6,12 @@ import 'src/screens/start_screen.dart';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
-  await dotenv.load(fileName: ".env");
+  try {
+    await dotenv.load(fileName: ".env");
+  } catch (e) {
+    // It's okay if the .env file is not found.
+    // This is expected in release builds.
+  }
 
   runApp(
     Provider<DeckRepository>(