fix Postgres service healthcheck

[DanRoscigno]

The Postgres service logs were full of errors as the healthcheck was looking for the DB shipment_db instead of pandashop:

postgres  | 2024-04-30 18:02:06.886 UTC [154] FATAL:  database "shipment_db" does not exist
postgres  | 2024-04-30 18:02:08.950 UTC [162] FATAL:  database "shipment_db" does not exist
postgres  | 2024-04-30 18:02:11.000 UTC [170] FATAL:  database "shipment_db" does not exist
postgres  | 2024-04-30 18:02:13.060 UTC [178] FATAL:  database "shipment_db" does not exist
postgres  | 2024-04-30 18:02:15.109 UTC [186] FATAL:  database "shipment_db" does not exist
postgres  | 2024-04-30 18:02:17.180 UTC [195] FATAL:  database "shipment_db" does not exist
postgres  | 2024-04-30 18:02:19.245 UTC [203] FATAL:  database "shipment_db" does not exist
postgres  | 2024-04-30 18:02:21.309 UTC [211] FATAL:  database "shipment_db" does not exist
postgres  | 2024-04-30 18:02:23.373 UTC [219] FATAL:  database "shipment_db" does not exist
postgres  | 2024-04-30 18:02:25.442 UTC [227] FATAL:  database "shipment_db" does not exist

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[JakeSCahill]

Thanks!