Fix TypeError: FileExtensionUpdated() takes no arguments

Fixed the error mentioned in the issue stactools-packages#31

src/stactools/sentinel3/file_extension_updated.py

@@ -34,8 +34,7 @@ def local_path(self, v: Optional[str]) -> None:
     def ext(
         cls, obj: pystac.Asset, add_if_missing: bool = False
     ) -> "FileExtensionUpdated":
-        super().ext(obj, add_if_missing)
-        return cls(obj)
+        return super().ext(obj, add_if_missing)
 
     @classmethod
     def get_schema_uri(cls) -> str: