(maint) change migrate trgm message to refer to 9.4
(maint) change migrate trgm message to refer to 9.4

Previously this gave the impression that 9.3 was allowed.

waynr/puppetdb,grimradical/puppetdb,mullr/puppetdb,waynr/puppetdb,senior/puppetdb,rbrw/puppetdb,mullr/puppetdb,wkalt/puppetdb,waynr/puppetdb,puppetlabs/puppetdb,waynr/puppetdb,rbrw/puppetdb,grimradical/puppetdb,puppetlabs/puppetdb,wkalt/puppetdb,rbrw/puppetdb,kbarber/puppetdb,rbrw/puppetdb,senior/puppetdb,wkalt/puppetdb,senior/puppetdb,grimradical/puppetdb,mullr/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,mullr/puppetdb,wkalt/puppetdb,puppetlabs/puppetdb,senior/puppetdb,grimradical/puppetdb,kbarber/puppetdb,kbarber/puppetdb,kbarber/puppetdb,mullr/puppetdb,rbrw/puppetdb