Python 3.13.4 C-extension builds link against python313t.lib on non-threaded Python

[cgohlke]

Bug report

Bug description:

Same issue as #133779, except this applies to the Python 3.13.4 production release.

CPython versions tested on:

3.13

Operating systems tested on:

Windows

Linked PRs

• [3.13] gh-135151: Fix incorrect packaging of pyconfig.h in Windows installer #135180

[zooba]

Easiest fix is to do the same as we did in 3.14, and stop trying to be clever about the default value. Though I'm still not even totally clear on how we're getting the wrong one - I guess Wix is messing up search path order or something.