chore: Stop explicitly copying pubspec.lock as flutter pub get generates it.

lib/main.dart

@@ -28,7 +28,7 @@ class MyApp extends ConsumerWidget {
           seedColor: Colors.blue,
           brightness: Brightness.light,
         ),
-        cardTheme: CardTheme(
+        cardTheme: CardThemeData(
           elevation: 2,
           shape: RoundedRectangleBorder(
             borderRadius: BorderRadius.circular(12),
@@ -41,7 +41,7 @@ class MyApp extends ConsumerWidget {
           seedColor: Colors.blue,
           brightness: Brightness.dark,
         ),
-        cardTheme: CardTheme(
+        cardTheme: CardThemeData(
           elevation: 2,
           shape: RoundedRectangleBorder(
             borderRadius: BorderRadius.circular(12),