(Feat) Add google

lib/screens/welcome_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 
 import '../theme.dart';
+import '../widgets/oauth_boutons.dart';
 import 'login_screen.dart';
 import 'signup_screen.dart';
 
@@ -57,6 +58,8 @@ class WelcomeScreen extends StatelessWidget {
                 ),
                 child: const Text('J\'ai déjà un compte'),
               ),
+              const SizedBox(height: 16),
+              const OAuthBoutons(),
               const SizedBox(height: 12),
             ],
           ),