cmake: fix python path with use multi-version python

[xz-dev]

If I use python3.13 as my system python version, but I use python3.12 to create venv, cmake will find /usr/bin/python3.13 but not venv

Because cmake will use the latest version.

From https://cmake.org/cmake/help/latest/module/FindPython3.html

Note
This hint has the lowest priority of all hints, so even if, for example, you specify IronPython first and CPython in second, a python product based on CPython can be selected because, for example with Python3_FIND_STRATEGY=LOCATION, each location will be search first for IronPython and second for CPython.

Refer: https://discourse.cmake.org/t/find-package-python3-is-not-finding-the-correct-python/10563

[github-actions]

Build size and comparison to main:

Section	Size	Difference
text	374512B	-16B
data	948B	0B
bss	63488B	0B

[FintasticMan]

Looks good to me! We could also set the CMP0094 policy to NEW, which would achieve the same thing, but I think this is more clear to readers of the code.