classmethod properties are removed in Python 3.13

[QuLogic]

Problem description

This was added in #519:

numcodecs/numcodecs/zstd.pyx

Lines 261 to 277 in 696e582

	@classmethod
	@property
	def default_level(cls):
	"""Returns the default compression level of the underlying zstd library."""
	return ZSTD_defaultCLevel()
	@classmethod
	@property
	def min_level(cls):
	"""Returns the minimum compression level of the underlying zstd library."""
	return ZSTD_minCLevel()
	@classmethod
	@property
	def max_level(cls):
	"""Returns the maximum compression level of the underlying zstd library."""
	return ZSTD_maxCLevel()

However, as of Python 3.11, using classmethod on property was deprecated, and has been removed in Python 3.13:
https://docs.python.org/3.13/library/functions.html#classmethod

Deprecated since version 3.11, removed in version 3.13: Class methods can no longer wrap other descriptors such as property().

This causes tests to fail on Python 3.13:

____________________________ test_native_functions _____________________________
    def test_native_functions():
        # Note, these assertions might need to be changed for new versions of zstd
>       assert Zstd.default_level == 3
E       AssertionError: assert <bound method default_level of <class 'numcodecs.zstd.Zstd'>> == 3
E        +  where <bound method default_level of <class 'numcodecs.zstd.Zstd'>> = Zstd.default_level
../../BUILDROOT/usr/lib64/python3.13/site-packages/numcodecs/tests/test_zstd.py:93: AssertionError

https://kojipkgs.fedoraproject.org/work/tasks/9111/120819111/build.log

Version and installation information

Please provide the following:

• Value of numcodecs.__version__ 0.13.0
• Version of Python interpreter 3.13.0b3
• Operating system (Linux/Windows/Mac) Fedora Rawhide
• How NumCodecs was installed (e.g., "using pip into virtual environment", or "using conda") from source

[QuLogic]

Ping? We're less than a month away from Python 3.13 final.

[dstansby]

I guess a blocker to this is running tests on Python 3.13. Do you know the best way to test on pre-release Python these days? We're currently using conda to manage Python in the tests, which last time I checked didn't ship pre-release versions of Python, but I'm open to moving to another way of managing Python in CI if it gives us pre-release Python.

[QuLogic]

For Matplotlib, we use actions/setup-python@v5 with allow-prereleases: true and the usual pip install. I don't know about all numcodecs dependencies though.