add PSOTGRES_PORT to frontend service

Description

after merging: #101
The tsm-frontend now also includes a POSTGRES-PORT env, which is used to add the port to the database url for a thing
This should also be included in the orchestration repo
for reference, see: https://codebase.helmholtz.cloud/ufz-tsm/tsm-frontend/-/blob/master/docker-compose.yml?ref_type=heads#L48