gtkfilechooserwidget: Mark string as no-c-format
gettext 0.22 recognizes %b as a C string format which not is true for date strings, so explicitly mark as no-c-format.
Should fix msgfmt -cv
problems the Persian translation ran into with the gtk-4-14 translation on l10n.gnome.org
(cherry picked from commit 5df9b1cb)