[titiler.xarray] update for Zarr 3.0

[vincentsarago]

https://zarr.dev/blog/zarr-python-3-release/

we also need to pin zarr to 2.0 https://github.com/developmentseed/titiler/actions/runs/12695652933/job/35388000642?pr=1067

[maxrjones]

The failing tests seem to fall into two categories.

1. TypeError: Unsupported type for store_like: 'FSMap'.

This is being tracked by pydata/xarray#9957 and zarr-developers/zarr-python#2706. I expect this functionality will get implemented upsteam (and can see if it's something I could help with), so the solution here is likely to keep the pin on Zarr Python < 3.0 until that feature is implemented and released.

2. TypeError: Object 0 has an invalid type for "path": int

It seems that int keys were likely automatically cast to strings in zarr python 2.0 but are not in zarr python 3.0. I think we could fix this easily on our end by parameterizing string keys rather than ints in

titiler/src/titiler/xarray/tests/test_io_tools.py

Line 132 in 5fab604

[0, 1, 2],

Even in the Zarr V2 spec, keys needed to be ASCII strings so this seems mostly a user error to me.