feat(api/Docker): automatically run migrations on container start

migrations do nothing when there's nothing to do and this allows easier version upgrades

api/compose/django/server.sh

@@ -1,3 +1,4 @@
 #!/bin/bash -eux
 python /app/manage.py collectstatic --noinput
+python /app/manage.py migrate
 gunicorn config.asgi:application -w ${FUNKWHALE_WEB_WORKERS-1} -k uvicorn.workers.UvicornWorker -b 0.0.0.0:5000 ${GUNICORN_ARGS-}

changes/changelog.d/1879.enhancement

@@ -0,0 +1 @@
+Apply migrations on API container start (!1879)