don't aggregate publishSigned/publishSignedLocal

We have to override all sbt-pgp stuff in .sbt files
because sbt-pgp uses plugin.settings and thus overrides
Build.scala configuration. So the no-op'ing of publishSigned
in some of the projects didn't work.
set git.baseVersion in ThisBuild not GlobalScope so it works

The git plugin sets in ThisBuild which overrides GlobalScope.
Snapshot release NEWS for 1.1.0-9f31d6308e7ebbc3d7904b64ebb9f61f7e22a968