Reapply "Use macos-latest for iOS arm64 simulator"

[radarhere]

No objections to #9258 being merged - it's just that the job passes when I run it, so I've created this to demonstrate that it does work at least sometimes. I don't know what any other next step would be.

[hugovk]

cc @freakboy3742: short version: the "iOS arm64 simulator" wheel is sometimes hanging and timing out when using macos-latest aka macos-15, but not with macos-14.

We switched to macos-latest just before yesterday's release, and that was fine, but it hung during the release so we went back to macos-14 to get the release out.

---

Yeah, it's strange, it passed yesterday in some runs but hung during the release build.

And the first two attempts on this PR hung and timed out:

• https://github.com/python-pillow/Pillow/actions/runs/18542963978/job/52854710770?pr=9259
• https://github.com/python-pillow/Pillow/actions/runs/18542963978/job/52866359531?pr=9259

But attempt 3 passed:

• https://github.com/python-pillow/Pillow/actions/runs/18542963978/job/52875100002?pr=9259

Comparing logs, I don't see much different: same macOS and runner versions.

We've plenty of time until the next release (2.5 months), we could merge this and hope it goes away by 2nd January..?

[freakboy3742]

@hugovk Ack. FWIW, see also this conversation on cibuildwheel, which is essentially the same problem being reported. Hopefully either I (or hopefully GitHub) will find a more permanent fix soon.