docker: Override entry point for celery containers
docker: Override entry point for celery containers

There is no need that the static file collection and migration
is executed every time when both the app itself and the celery
workers are started.
This change overrides the docker entry point for the celery
workers so they don't run the migrations too.
porksmash/swarfarm,porksmash/swarfarm,porksmash/swarfarm,PeteAndersen/swarfarm,PeteAndersen/swarfarm,porksmash/swarfarm,PeteAndersen/swarfarm,PeteAndersen/swarfarm