Issue with FileAnnotations using simple transfer

[maartenpaul]

When transferring some data from OMERO using omero-cli-transfer with the --simple flag I got the following error:

....
  File "D:\OMERO\omero_transfer\.pixi\envs\default\Lib\site-packages\omero_cli_transfer.py", line 199, in _wrapper
    return func(self, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\OMERO\omero_transfer\.pixi\envs\default\Lib\site-packages\omero_cli_transfer.py", line 319, in pack
    self.__pack(args)
  File "D:\OMERO\omero_transfer\.pixi\envs\default\Lib\site-packages\omero_cli_transfer.py", line 570, in __pack
    self._fix_pixels_image_simple(ome, folder, md_fp)
  File "D:\OMERO\omero_transfer\.pixi\envs\default\Lib\site-packages\omero_cli_transfer.py", line 456, in _fix_pixels_image_simple
    if isinstance(ann.value, str) and\
                  ^^^^^^^^^
  File "D:\OMERO\omero_transfer\.pixi\envs\default\Lib\site-packages\ome_types\_mixins\_base_type.py", line 152, in __getattr__
    return super().__getattr__(key)  # type: ignore
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\OMERO\omero_transfer\.pixi\envs\default\Lib\site-packages\pydantic\main.py", line 1026, in __getattr__
    raise AttributeError(f'{type(self).__name__!r} object has no attribute {item!r}')
AttributeError: 'FileAnnotation' object has no attribute 'value'

It seems that the issue is that the function _fix_pixels_image_simple assumes all annotations have a value attribute but apparently not all annotation types do.
With this PR I added a check for the annotation type first. Please adjust if necessary.

[erickmartins]

thanks for the report and the fix! note to self for later: this might be worth implementing as a try-except checking for AttributeError