org-element-cache-map: Increase minimal Emacs version in 717a847d6
* lisp/org-element.el (org-element-cache-map): Do not byte-compile
FUNC in Emacs 28 as well. Some variants of Emacs 28 do not
byte-compile the lambda correctly [1].
[1] https://list.orgmode.org/87tuha62rq.fsf@localhost/T/#ma9f23ef9e96de01c53451f40d097e4ce2fd51571