limit postgres version in CI (#2040)

Author: haritamar

tests/e2e_dbt_project/docker-compose.yml

@@ -2,7 +2,7 @@ version: "3.8"
 
 services:
   postgres:
-    image: postgres
+    image: postgres:15
     ports:
       - "127.0.0.1:5432:5432"
     command: postgres -c max_connections=500