Bump Version to 3.1.16

Time for a new Gpg4win release and anyway a good time
to do a bump.
2 jobs for master in 14 minutes and 27 seconds (queued for 125 minutes and 34 seconds)
Status Name Job ID Coverage
  Build
passed build_clazy_clang_tidy #111006

00:09:56

passed linux kf5-qt5 qt5.15 #111005

00:04:31

0.0%