message: bump debian package version.
diff: +peercoin (0.6.3-1) stable; urgency=low
  +
  + * New upstream release, improved desktop integration.
  +
  + -- <peerchemist@protonmail.ch> Fri, 20 Apr 2018 14:59:20 +0000
  +
  peercoin (0.6.2-2) stable; urgency=low
  * More polish for the package.
  