Attributes.__delitem__ is broken

[dcherian]

Zarr version

v3.0.5

Description

Deleting zarr_group.attrs["key"] doesn't work.

zarr-python/src/zarr/core/attributes.py

Lines 28 to 31 in 38a2417

	def __delitem__(self, key: str) -> None:
	new_attrs = dict(self._obj.metadata.attributes)
	del new_attrs[key]
	self._obj = self._obj.update_attributes(new_attrs)

After #2870 , update_attributes means update, not overwrite.

Steps to reproduce

...

Additional output

No response