force postgres 14 for func tests (#1813)

the postgres 15 image (released two days ago) has a permission issue. proper fix will follow

.github/workflows/bats-postgres.yml

@@ -14,7 +14,7 @@ jobs:
     timeout-minutes: 20
     services:
       database:
-        image: postgres:latest
+        image: postgres:14
         env:
           POSTGRES_PASSWORD: "secret"
         ports: