docker-compose.yml: Add health check for "db" container

requested review from @anusha

assigned to @anusha

added Ready for review label

removed Ready for review label

added Approved label

changed target branch from develop to test-0.3.7-b

This has been merged into develop as a part of merge request https://gitlab.ruhr-uni-bochum.de/FDM/rdm-system/rdms/-/merge_requests/162

closed