Add numpy to mypy pre-commit check env

[dstansby]

This reveals some typing errors that aren't spotted if numpy is absent. This will fail for now until I make the fixes.

TODO:

• Add unit tests and/or doctests in docstrings
• Add docstrings and API docs for any new/modified user-facing classes and functions
• New/modified features documented in docs/tutorial.rst
• Changes documented in docs/release.rst
• GitHub Actions have all passed
• Test coverage is 100% (Codecov passes)

[dstansby]

@normanrz is there any chance you could look at and fix the errors in zarr.codecs.zstd?
@madsbk is there any chance you could look at and fix the errors in zarr.buffer?

[madsbk]

@normanrz is there any chance you could look at and fix the errors in zarr.codecs.zstd? @madsbk is there any chance you could look at and fix the errors in zarr.buffer?

I am working on a protocol for ArrayLike and NDArrayLike to support both numpy and cupy. It should fix (at least) some of the errors :)

See #1899

[normanrz]

@normanrz is there any chance you could look at and fix the errors in zarr.codecs.zstd?

Done. I also removed test.py which I assume was added unintentionally.

[dstansby]

Thanks! Yeah, test.py definitely wasn't meant to be committed

[dstansby]

I've ignored the errors in zarr.buffer for now; when this PR gets merged, @madsbk could you make sure #1899 is rebased on top if it and this line is removed so errors are caught:

https://github.com/dstansby/zarr-python/blob/56de78aa8f0b2cd3b5bd82f666acc085faf86004/pyproject.toml#L233