fix input file def

Author: lohanidamodar

example/README.md

@@ -41,7 +41,7 @@ Upload File:
 ```dart
 Storage storage = Storage(client);
 
-InputFile file = InputFile(path: './path-to-file/image.jpg', fileName: 'image.jpg');
+InputFile file = InputFile(path: './path-to-file/image.jpg', filename: 'image.jpg');
 
 storage.createFile(
     bucketId: '[BUCKET_ID]',

lib/src/input_file.dart

@@ -3,7 +3,7 @@ import 'package:http/http.dart' show MultipartFile;
 class InputFile {
   final MultipartFile? file;
   final String? path;
-  final String? fileName;
+  final String? filename;
 
-  InputFile({this.file, this.path, this.fileName});
+  InputFile({this.file, this.path, this.filename});
 }