Upgrade postgres 11.6-r0 -> 11.7-r0 in server/Dockerfile (fix e2e tests)
Created by: mrnugget
e2 tests have been failing (example) because of this:
#7 2.216 ERROR: unsatisfiable constraints:
#7 2.281 postgresql-12.2-r0:
#7 2.281 breaks: world[postgresql=11.6-r0]
#7 2.281 postgresql-contrib-12.2-r0:
#7 2.281 breaks: world[postgresql-contrib=11.6-r0]
which @unknwon reported in the #buildkite
channel.