[Tails-l10n] Please check PO files in the stable branch for …

Hi,

Can someone please run `check_po.sh` on po/* in the 'stable' branch? I
ran it myself and got:

    W: ./zh.po: no-plural-forms-header-field 'nplurals=<n>; plural=
    <expression>'

but I'm unsure of how to deal with it.

Cheers!