DEP: Pin cython>=3

[snowman2]

Related: rasterio/rasterio#2875

[mwtoews]

Thanks, the long-awaited Cython 3.0 has been released (e.g. InfoWorld).

The CI tests are still using Cython~=0.29.29 (from -r requirements-dev.txt (line 4)).

Are there any relevant items in the migration guide that should be considered?

[snowman2]

The CI tests are still using Cython~=0.29.29 (from -r requirements-dev.txt (line 4)).

Thanks - updated.

[snowman2]

Are there any relevant items in the migration guide that should be considered?

Possibly, but nothing pops out to me at the moment.

[mwtoews]

With a local build, the only thing that pops up for me is:

warning: fiona/_env.pyx:152:0: The 'IF' statement is deprecated and will be removed in a future Cython version. Consider using runtime conditions or C macros instead. See cython/cython#4310

this can be addressed later.

[snowman2]

See #1137