Service will fail to boot

I think mentioned this could happened in [comment](https://github.com/hummingbird-project/swift-jobs/pull/5#discussion_r1730402817) I have a small [repository](https://github.com/thoven87/swift-jobs-postgres) setup where the service will fail to start since `setMedata` or `getMetada` is being called before [postgres-nio](https://github.com/vapor/postgres-nio/tree/main) is ready. This issue is not present with the redisstack and confirmed it works fine. The Postgres implementation will yield ```sh [PostgresNIO] Trying to lease connection from `PostgresClient`, but `PostgresClient.run()` hasn't been called yet. ``` and the service will hang. There needs to be a warning on the Swift Jobs Postgres implementation until this issue is fixed in PostgresNIO cc @fabianfett @adam-fowler