Test against Zarr v3 in CI

[TomNicholas]

If we add CI workflows that use the bleeding edge versions of upstream dependencies, we can use it to test against zarr-python-v3.

If we add another env that uses upstream versions but only the minimum dependencies (i.e. no kerchunk), then we can use that to test Icechunk integration against.

We may also want to add another env to test V3 with kerchunk.

This way we can start testing every feature against each version of key dependencies, in a way that will still be a somewhat sane setup even after the whole ecosystem works with zarr-python-v3.

[TomNicholas]

I just realised that what I'm trying to achieve is the same as what @ghidalgo3 already suggested in #182 (comment). The difference is that now we can run the tests (skipping a lot of them #259) without kerchunk installed