clean up cross-publishing #458
Description
Right now, publishing does a +publish and then separate explicit publish invocations for 2.13 and 3.3 versions of codegen.
IIRC this is because in earlier versions of SBT, there was a problem with the sbt plugin (which is only published for 2.12) depending on codegen (when it's configured to be published for 2.13 and 3.3 as well).
It'd be great to figure out if that sbt limitation still exists. If so, try and remove it. If not, cross-publish regularly.