Fix user type

[tun0]

Should fix this endless loop:

  # module.candidates_db.google_sql_user.admin_user must be replaced
-/+ resource "google_sql_user" "admin_user" {
      - host     = "" -> null
      ~ id       = "postgres//primary1-psql13" -> (known after apply)
        name     = "postgres"
      ~ project  = "candidates-prod-123456" -> (known after apply)
      ~ type     = "" -> "BUILT_IN" # forces replacement
        # (2 unchanged attributes hidden)
    }