TF-3410 Fix wrong text style avatar icon

Signed-off-by: dab246 <tdvu@linagora.com>

lib/features/base/widget/email_avatar_builder.dart

@@ -1,5 +1,6 @@
 
 import 'package:core/presentation/extensions/color_extension.dart';
+import 'package:core/presentation/utils/theme_utils.dart';
 import 'package:core/presentation/views/image/avatar_builder.dart';
 import 'package:flutter/material.dart';
 import 'package:model/email/presentation_email.dart';
@@ -19,10 +20,7 @@ class EmailAvatarBuilder extends StatelessWidget {
     return (AvatarBuilder()
       ..text(emailSelected.getAvatarText())
       ..size(50)
-      ..addTextStyle(const TextStyle(
-          fontWeight: FontWeight.bold,
-          fontSize: 21,
-          color: Colors.white))
+      ..addTextStyle(ThemeUtils.textStyleHeadingH4(color: Colors.white))
       ..backgroundColor(AppColor.colorAvatar)
       ..avatarColor(emailSelected.avatarColors))
     .build();