PyUnstable_GC_VisitObjects should traverse the permanent generation on the free-threaded build as well

[DinoV]

Bug report

Bug description:

See #131740

This was fixed on the non-free threaded builds but the free-threaded builds don't include them.

CPython versions tested on:

3.16, CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-156395: Report frozen objects on free-threaded GC build #156396
• [3.15] gh-156395: Report frozen objects on free-threaded GC build (GH-156396) #156420
• [3.14] gh-156395: Report frozen objects on free-threaded GC build (GH-156396) #156421