[V3] Update minimum supported Python and Numpy versions

[jhamman]

This PR bumps the minimum supported Python and Numpy versions for the V3 branch. These are aligned with Spec0000 (see #1616) assuming we are planning to release in late Q1 or Q2 of 2024.

Knowing that we are developing against Python 3.10+ will help smooth over some syntax pain, especially when working on the goal of 100% type hint coverage.

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)

[pep8speaks]

Hello @jhamman! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file zarr/tests/test_codecs_v3.py:

Line 76:20: E203 whitespace before ':'
Line 76:46: E203 whitespace before ':'
Line 76:72: E203 whitespace before ':'
Line 214:20: E203 whitespace before ':'
Line 214:46: E203 whitespace before ':'
Line 214:72: E203 whitespace before ':'

• In the file zarr/v3/codecs/sharding.py:

Line 152:48: E203 whitespace before ':'

• In the file zarr/v3/store.py:

Line 301:44: E203 whitespace before ':'
Line 313:30: E203 whitespace before ':'