[MNT] python 3.13 support, add 3.13 to test matrix

[fkiraly]

Extends the bounds in pyproject.toml to add experimental support for python 3.13, and adds testing on 3.13 to the test matrix.

Full 3.13 support to be added with 2.7.0.

[fkiraly]

numpy seems incompatible with windows, this is the failure:

rm -rf testdir
mkdir -p testdir
cp .coveragerc testdir
cp setup.cfg testdir
python -m pytest
<frozen importlib._bootstrap>:488: Warning: Numpy built with MINGW-W64 on Windows 64 bits is experimental, and only available for 
testing. You are advised not to use it for production. 

CRASHES ARE TO BE EXPECTED - PLEASE REPORT THEM TO NUMPY DEVELOPERS
C:\hostedtoolcache\windows\Python\3.13.0\x64\Lib\site-packages\numpy\core\getlimits.py:225: RuntimeWarning: invalid value encountered in exp2
  epsneg_f128 = exp2(ld(-113))
C:\hostedtoolcache\windows\Python\3.13.0\x64\Lib\site-packages\numpy\core\getlimits.py:226: RuntimeWarning: invalid value encountered in exp2
  tiny_f128 = exp2(ld(-16382))
C:\hostedtoolcache\windows\Python\3.13.0\x64\Lib\site-packages\numpy\core\getlimits.py:240: RuntimeWarning: invalid value encountered in exp2
  eps=exp2(ld(-112)),
C:\hostedtoolcache\windows\Python\3.13.0\x64\Lib\site-packages\numpy\core\getlimits.py:41: RuntimeWarning: invalid value encountered in nextafter
  self._smallest_subnormal = nextafter(
C:\hostedtoolcache\windows\Python\3.13.0\x64\Lib\site-packages\numpy\core\getlimits.py:52: RuntimeWarning: invalid value encountered in log10
  self.precision = int(-log10(self.eps))
make: *** [Makefile:25: test] Error -1073741819

[fkiraly]

Hm, must be coming from one of the softdeps, because the no-extras run seems fine. I suspect scikit-survival since in the install phase it is the only dep that builds.