[BUG] Fix upload attachment

model/lib/upload/file_info.dart

@@ -1,5 +1,6 @@
 
 import 'package:equatable/equatable.dart';
+import 'package:mime/mime.dart';
 
 class FileInfo with EquatableMixin {
   final String fileName;
@@ -12,6 +13,8 @@ class FileInfo with EquatableMixin {
     return FileInfo('', '', 0);
   }
 
+  String get mimeType => lookupMimeType(filePath) ?? 'application/json; charset=UTF-8';
+
   @override
   List<Object> get props => [fileName, filePath, fileSize];
 }

model/pubspec.yaml

@@ -57,6 +57,9 @@ dependencies:
   # http_parser
   http_parser: 4.0.0
 
+  # mime
+  mime: 1.0.1
+
 dev_dependencies:
   flutter_test:
     sdk: flutter