[BUG] pylibraft compilation errors with Cython 3.1 nightlies

[jameslamb]

Describe the bug

I recently observed pylibraft compilation errors in this project's pip devcontainer and not in any other wheel builds, like this:

Error compiling Cython file:
------------------------------------------------------------

cdef device_matrix_view[const_float, int64_t, row_major]
^

/home/coder/raft/python/pylibraft/pylibraft/common/mdspan.pyx:203:0: Function signature does not match previous declaration

ref: #2490 (comment)

The root cause, per #2490 (comment), is that those builds were pulling in a pre-release of Cython 3.1.

Downloading Cython-3.1.0a1-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl.metadata (3.2 kB)

That was "fixed" in #2490 by pinning to cython<=3.0.11, but we should work to remove that ceiling.

Specifically, we should:

1. create a smaller, not-RAFT-specific minimum reproducible example
2. modify RAFT source code and/or submit a bug report upstream with Cython
3. remove the ceiling

Steps/Code to reproduce bug

Modify this project's Cython dependency to something like `cython>=3.1.0a0' and try to build in the pip devcontainer.

Expected behavior

Successful builds of pylibraft with Cython 3.1.

Environment details (please complete the following information):

N/A

Additional context

N/A