Drop Zarr 2.x Support

[ericspod]

Is your feature request related to a problem? Please describe.
Zarr 3.x moved a number of types around and few other compatibility breaking changes. We currently try to support 2.x and 3.x in places like here but we should consider when to drop support for 2.x. This would help improve the typing of this module as well.

[jamesobutler]

Zarr 3.0 requires Python 3.11 and newer. This is because they follow SPEC0 as seen in the PR that dropped Python 3.10 support in zarr-developers/zarr-python@0e4cc7e.

As previously mentioned at #8303 (comment), MONAI could consider adopting SPEC0 as well which would mean bumping the minimum required Python version from 3.9 to 3.11 if it was done today.

MONAI/setup.cfg

Line 36 in 7c26e5a

python_requires = >= 3.9