fix: move baseUrl to constant.dart

lib/src/constans.dart

+String baseUrl = 'https://ilhammaulana.pythonanywhere.com/api/v1';
\ No newline at end of file

lib/src/providers/auth_provider.dart

@@ -8,8 +8,9 @@ import 'package:http/http.dart' as http;
 import 'package:library_app/src/models/token.dart';
 import 'package:library_app/src/models/user.dart';
 
+import 'package:library_app/src/constans.dart';
+
 class AuthProvider with ChangeNotifier {
-  String baseUrl = 'https://ilhammaulana.pythonanywhere.com/api/v1';
   String? message;
 
   User? user;

lib/src/providers/book_provider.dart

@@ -3,8 +3,9 @@ import 'dart:convert';
 import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
 
+import 'package:library_app/src/constans.dart';
+
 class BookProvider with ChangeNotifier {
-  String baseUrl = 'https://ilhammaulana.pythonanywhere.com/api/v1';
   List<dynamic>? books;
   List<dynamic>? categories;
   Category? category;