Fix unit tests

qim3d/filters/_common_filter_methods.py

qim3d/gui/annotation_tool.py

qim3d/gui/iso3d.py

qim3d/gui/layers2d.py

qim3d/gui/local_thickness.py

qim3d/io/_convert.py

qim3d/io/_downloader.py

qim3d/io/_loading.py

qim3d/io/_ome_zarr.py

qim3d/io/_saving.py

qim3d/io/_sync.py

qim3d/ml/_data.py

qim3d/ml/models/_unet.py

qim3d/operations/_common_operations_methods.py

qim3d/processing/_local_thickness.py

qim3d/processing/_structure_tensor.py

qim3d/tests/filters/test_filters.py

qim3d/tests/io/test_downloader.py

qim3d/tests/ml/models/test_unet.py

qim3d/tests/ml/test_models.py