Fix cron script issues related to docker version upgrade on new servers

[dchiller]

As noted in this Docker documentation, when Docker compose specifications migrated from V1 to V2, the word separator in the default container name changed from an underscore to a hyphen. Our new servers, with their upgraded version of Docker, use the hyphen. Since the documentation suggests an underlying networking reason for this change, this PR implements it.

The relevant container name in the db_backup.sh script is changed (cantusdb_postgres_1 to cantusdb-postgres-1).

This PR also updates all docker-compose files in this repo to specify the container name (although our scripts now conform to this naming convention, it doesn't hurt to make it explicit).

The docker-compose command was also deprecated with the version of Docker server used on the new servers. This PR adjusts the manage.sh cron script to use docker compose rather than docker-compose.

Closes #1489.

A companion PR in the ansible set-up (https://github.com/dact-chant/ansible.cantus-db/pull/39) makes the analogous change in the docker-compose.yml template.