[pgp] Update manifest.ini

pgp/manifest.ini

 [info]
 name: PGP
 short_name: PGP
-version: 1.2.30
+version: 1.2.31
 description: PGP encryption as per XEP-0027
 authors: Philipp Hörist <philipp@hoerist.com>
 homepage: https://dev.gajim.org/gajim/gajim-plugins/wikis/pgpplugin