CASSPYTHON-3 Introduce pyproject.toml to explicitly declare build dependencies

[absurdfarce]

Original motivation is CASSPYTHON-3, a lifted version of PYTHON-1428. These changes also take care of PYTHON-1334 ("Consider migrating dependency, other information in setup.py into pyproject.toml") and PYTHON-1421 ("Adapt setup.py to deprecation of distutils")

This PR represents a pretty significant re-working of setup.py so the question of what kind of release it belongs in is a very real one. The original motivation was to fix a specific problem with the wheels for 3.29.3 but so far I haven't found a way to do that other than the mechanism outlined here. That question is being considered on CASSPYTHON-3; we'll use this PR to discuss and review the changes themselves.

[absurdfarce]

Ping @millerjp as well

[absurdfarce]

I've run this through our wheel build process for Python 3.12 against ARM64 and x86_64 Ubuntu. In both cases all expected native code was preserved.

Might still have a problem though:

(wheel-validate-venv) mersault@stravinsky:~/Downloads$ python3
Python 3.12.11 (main, Sep  2 2025, 14:20:15) [Clang 20.1.4 ] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from cassandra.cmurmur3 import murmur3
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: /home/mersault/Downloads/wheel-validate-venv/lib/python3.12/site-packages/cassandra/cmurmur3.cpython-312-aarch64-linux-gnu.so: undefined symbol: rotl64
>>> import cassandra.io.libevwrapper as libev
>>>

I mean... at least libev worked...

[absurdfarce]

I removed the the "-s" arg to gcc from CFLAGS in order to diagnose the problem:

$ git show HEAD
commit 2d6517477b44cce69faa7c1b9e08b5525c2eb15e (HEAD -> python1428, origin/python1428)
Author: absurdfarce <bret.mcguire@ibm.com>
Date:   Tue Dec 23 13:21:34 2025 -0600

    Temporarily remove stripping of symbols from shared objects in order to try and diagnose an issue

diff --git a/.github/workflows/build_wheels_linux.yml b/.github/workflows/build_wheels_linux.yml
index c8d5af1..88628ef 100644
--- a/.github/workflows/build_wheels_linux.yml
+++ b/.github/workflows/build_wheels_linux.yml
@@ -13,7 +13,6 @@ jobs:
       CIBW_TEST_REQUIRES: pytest mock pure-sasl eventlet
       CIBW_TEST_COMMAND: echo "wheel is installed"
       CIBW_BEFORE_ALL: yum install -y libev libev-devel
-      CIBW_ENVIRONMENT: CFLAGS='-s'
       CIBW_BUILD_VERBOSITY: 3
     steps:
       - uses: actions/checkout@v4

and the problem... went away?!?!?!?!?!

[absurdfarce]

Worth noting that the wheels for 3.29.3 available from pypi also have this issue. Wheels for 3.29.2 from pypi do not have this problem. We introduced the stripping of symbols on 7/30/2024 as the fix for PYTHON-1387. Weird thing is that 3.29.2 was released in September of 2024 so wheels built there would've included that fix.... and they appear fine.

I can't really explain any of this yet. The error itself doesn't make sense... and the chronology doesn't introduce an obvious point where a regression like this could've come in.

[absurdfarce]

Moving discussion about the wheel build issue to a distinct issue on python-driver-wheels. Let's keep this PR focused on conversation about the pyproject.toml conversion.

[bschoening]

add in classifiers "License :: OSI Approved :: Apache Software License",

[bschoening]

add 'homepage', and if it exists, 'changelog'