Disable the automatic use of latest gms-artic containers

[pbiology]

What needs to be done:
When new docker containers from gms-artic is built, we automatically download them and use them in production. This can cause issues if the new containers contain updates we haven't tested in production.

Suggestions on how to get it done:

• Make sure we understand how we are using the gms-artic containers
• Check for a solution where we don't always use the latest version

What are the arguments for getting it done:

• Will cause less problems for production if gms-artic is updated without us knowing it

Task is considered finished when:

• We have control over what containers are used in production

[talnor]

Updates are due to that the pangolin-data is installed in the docker images (and needs to be updated frequently). If the data is located elsewhere, we can use fixed image versions. Related issue in gms-artic here: genomic-medicine-sweden/gms-artic#81

[talnor]

As of PR #164 we use a separate docker image for pangolin. Meaning that we have a more robust set up and have control over the other tools that are used. However, the issue remains for updates of pangolin in gms-artic.

Updating urgency and gain accordingly.