Fix Docker setup and add back back an entrypoint

* Also add special deps for argon2 support inside the Alpine image
* Make sure yarn install is triggered

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

docker-compose.yml

@@ -30,7 +30,7 @@ services:
       MOBILIZON_DATABASE_USERNAME: postgres
       MOBILIZON_DATABASE_DBNAME: mobilizon_dev
       MOBILIZON_DATABASE_HOST: postgres
-    command: "mix phx.migrate_serve"
+    command: "mix phx.deps_migrate_serve"
 volumes:
   pgdata:
   .: