chore: Update docker-compose.yml (bitmagnet-io#370)

`gluetun` may take a while before a VPN connection is established. Before that completes, `bitmagnet` will immediately start attempting to make connection attempts, which will fail.

`gluetun` provides a healthcheck via its `Dockerfile`: https://github.com/qdm12/gluetun-wiki/blob/main/faq/healthcheck.md

Co-authored-by: mgdigital <mgdigital@users.noreply.github.com>

Author: dashed

docker-compose.yml

@@ -20,6 +20,8 @@ services:
     depends_on:
       postgres:
         condition: service_healthy
+      gluetun:
+        condition: service_healthy
     command:
       - worker
       - run