fix storage base class str method

pangeo_forge_runner/storage.py

@@ -69,7 +69,7 @@ def __str__(self):
  fsspec_args_filtered = ", ".join(
  f"{k}=<{type(v).__name__}>" for k, v in self.fsspec_args.items()
  )
- return f'{self.pangeo_forge_target_class.__name__}({self.fsspec_class.__name__}({fsspec_args_filtered}, root_path="{self.root_path}")'
+ return f'{self.pangeo_forge_target_class}({self.fsspec_class.__name__}({fsspec_args_filtered}, root_path="{self.root_path}")'
 
 
 class TargetStorage(StorageTargetConfig):