d/control: Debian buster now has PostgreSQL 11

debian/control

@@ -7,8 +7,8 @@ Build-Depends: alembic,
                debhelper (>= 11.2~) | fakeroot,
                dpkg-dev (>= 1.19.0.5) | fakeroot,
                jq,
-               postgresql-10 | postgresql-9.6 | postgresql-9.4,
-               postgresql-10-debversion | postgresql-9.6-debversion | postgresql-9.4-debversion,
+               postgresql-11 | postgresql-9.6 | postgresql-9.4,
+               postgresql-11-debversion | postgresql-9.6-debversion | postgresql-9.4-debversion,
                python-all-dev,
                python-apt,
                python-debian,