Add curl package to Dockerfile.buster to allow for healthchecks (swarm, k8s, etc.)

[decentral1se]

Describe the problem to be solved

With docker swarm configs, you typically see a thing like this:

    healthcheck:
      test: ["cmd", "curl", "-f", "http://localhost:9000"]
      interval: 30s
      timeout: 10s
      retries: 10
      start_period: 10s

This allows swarm to understand when containers are healthy and do zero downtime deploys.

Curl appears to be missing from the default image published.

Describe the solution you would like:

Let's install curl in the default docker images.

Describe alternatives you have considered

Wget isn't there either, so it seems we're missing that approach.

[decentral1se]

➜  peertube (main) ✗ docker run chocobozzz/peertube:v3.1.0-buster which curl 
➜  peertube (main) ✗ docker run chocobozzz/peertube:v3.1.0-buster which wget