Fixed file param bug

Author: eldadfux

docs/examples/storage/create-file.md

@@ -10,7 +10,7 @@ void main() { // Init SDK
     .setProject('5df5acd0d48c2') // Your project ID
   ;
   Future result = storage.createFile(
-    file: '',
+    file: await MultipartFile.fromFile('./path-to-files/image.jpg', 'image.jpg'),
   );
 
   result

lib/services/storage.dart

@@ -33,7 +33,7 @@ class Storage extends Service {
      /// assigned to read and write access unless he has passed custom values for
      /// read and write arguments.
      ///
-    Future<Response> createFile({required String file, List read = const [], List write = const []}) {
+    Future<Response> createFile({required MultipartFile file, List read = const [], List write = const []}) {
         final String path = '/storage/files';
 
         final Map<String, dynamic> params = {