Relax constraint on numpy during type checking

[DimitriPapadopoulos]

Since https://github.com/numpy/numpy/issues/28034 has been resolved, try unpinning numpy.

Also, the version of google-crc32c is already constrained here: https://github.com/zarr-developers/zarr-python/blob/9f69611d3957c99653509c7cca7db96b2c395f37/pyproject.toml#L38

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/user-guide/*.md
• [ ] Changes documented as a new file in changes/
• [ ] GitHub Actions have all passed
• [ ] Test coverage is 100% (Codecov passes)