Support matrix

This is what the Nuwa toolchain tests today. Anything else may work, but is not a supported claim.

Item	Status
CPython 3.10, 3.11, 3.12, 3.13, 3.14	Tested
Python 3.9	Dropped in nuwa-build 0.5.0
Free-threaded CPython (`cp314t`)	Not tested (nimpy not verified)
PyPy	Not tested
Linux wheels	manylinux x86_64 and aarch64 on native runners
musllinux	Skipped (official Nim binaries are glibc)
Linux aarch64	Tested on `ubuntu-24.04-arm` with the official `linux_arm64` Nim archive
macOS	Native Intel or Apple Silicon archive
Windows	64-bit; MinGW runtimes statically linked by default
Nim	2.2.x in CI and the Action default (`2.2.10`)

Versions for the current line-up: