Switch to PostGIS image.

services/postgres.hcl

@@ -16,7 +16,7 @@ job "postgres" {
       driver = "docker"
 
       config {
-        image = "postgres:15-alpine"
+        image = "postgis/postgis:15-3.4-alpine"
         ports = ["db"]
         volumes = [ "/data/compute/appdata/postgres:/var/lib/postgresql/data" ]
       }