Document the lifetime of `PyUnicode_AsUTF8String` (GH-92325)

The current wording implied this, but didn't state it explicitly.
(cherry picked from commit 740da8d37a84638f4a8893bee3648f36fc6beb0f)

Co-authored-by: Matt Wozniski <godlygeek@gmail.com>

Miss Islington (bot) committed 4y ago

367faf71eae963e613cb4404e24748c91baa4190

Parent: 3db0e0b

Committed by GitHub <noreply@github.com> on 5/6/2022, 9:55:01 AM