Remove all pg12 traces so pg_wrapper doesn't get confused

Remove all pg12 traces so pg_wrapper doesn’t get confused

diff --git a/templates/postgres.10.template.yml b/templates/postgres.10.template.yml
index 63f06bd..fb5b252 100644
--- a/templates/postgres.10.template.yml
+++ b/templates/postgres.10.template.yml
@@ -19,7 +19,7 @@ hooks:
        to: sv start postgres || exit 1
 
 run:
-  - exec: apt-get remove -y postgresql-12 postgresql-client-12 postgresql-contrib-12
+  - exec: DEBIAN_FRONTEND=noninteractive apt-get purge -y postgresql-12 postgresql-client-12 postgresql-contrib-12
   - exec: apt-get update && apt-get install -y postgresql-10 postgresql-client-10 postgresql-contrib-10
   - exec: mkdir -p /shared/postgres_run
   - exec: chown postgres:postgres /shared/postgres_run

GitHub sha: 3e465a25