[Fix]: fix checking masks on MMDetWandbHook (open-mmlab#8455)

[nanpuhaha]

Motivation

To fix errors described on #8455.

Exception: input type is not supported.

Modification

Before checking masks is not None, if masks is the list of None, then change to None.

masks = [None, None, ..., None]
masks = None if set(masks) == {None} else masks

masks = None if set(masks) == {None} else masks     # 👈 new lines
if masks is not None:
    wandb_masks = self._get_wandb_masks(
        masks,
        labels,
        is_poly_mask=True,
        height=img_height,
        width=img_width)
else:
    wandb_masks = None

[CLAassistant]

All committers have signed the CLA.

[Cxuery]

Which code file should I modify, in which line？

[OpenMMLab-Assistant001]

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