Restore syntax highlighting in Emacs 30 or newer.
Reported by Sab Pyrope <sab.pyrope@gmail.com> in
<https://lists.gnu.org/archive/html/bug-gettext/2025-03/msg00017.html>
and by Julien Palard <julien@palard.fr> in
<https://lists.gnu.org/archive/html/bug-gettext/2025-10/msg00000.html>.
It's a regression in Emacs 30, in commit
17e26cf57e18c5df2172a7049591d89fc53b3fb6 .
* gettext-tools/emacs/HACKING: Document how to bisect Emacs regressions.
* gettext-tools/emacs/po-mode.el (po-mode-version-string): Bump to 2.31.
(po-mode): Invoke run-mode-hooks instead of run-hooks.
* NEWS: Mention the fix.