Fix analysis warnings in `drift_sqflite` example

drift_sqflite/example/lib/bloc.dart

@@ -1,5 +1,4 @@
 import 'package:example/database/database.dart';
-import 'package:drift_sqflite/drift_sqflite.dart';
 import 'package:drift/drift.dart';
 import 'package:rxdart/rxdart.dart';
 

drift_sqflite/example/lib/main.dart

@@ -19,7 +19,7 @@ class MyApp extends StatelessWidget {
           primarySwatch: Colors.orange,
           typography: Typography.material2018(),
         ),
-        home: HomeScreen(),
+        home: const HomeScreen(),
       ),
     );
   }

drift_sqflite/example/lib/widgets/add_category_dialog.dart

@@ -3,6 +3,8 @@ import 'package:example/bloc.dart';
 import 'package:provider/provider.dart';
 
 class AddCategoryDialog extends StatefulWidget {
+  const AddCategoryDialog({Key? key}) : super(key: key);
+
   @override
   _AddCategoryDialogState createState() => _AddCategoryDialogState();
 }

drift_sqflite/example/lib/widgets/categories_drawer.dart

@@ -49,7 +49,8 @@ class CategoriesDrawer extends StatelessWidget {
                 ),
                 onPressed: () {
                   showDialog(
-                      context: context, builder: (_) => AddCategoryDialog());
+                      context: context,
+                      builder: (_) => const AddCategoryDialog());
                 },
               ),
             ],

drift_sqflite/example/lib/widgets/homescreen.dart

@@ -9,6 +9,8 @@ import 'package:provider/provider.dart';
 // ignore_for_file: prefer_const_constructors
 
 class HomeScreen extends StatefulWidget {
+  const HomeScreen({Key? key}) : super(key: key);
+
   @override
   HomeScreenState createState() {
     return HomeScreenState();
@@ -33,7 +35,7 @@ class HomeScreenState extends State<HomeScreen> {
       body: StreamBuilder<List<EntryWithCategory>>(
         stream: bloc.homeScreenEntries,
         builder: (context, snapshot) {
-          print(snapshot);
+          debugPrint(snapshot.toString());
 
           if (!snapshot.hasData) {
             return const Align(