fix mongo healthcheck yaml formatting

docker-compose.tmpl.yml

@@ -100,6 +100,7 @@ services:
   mongodb:
     image: mongo:4.4
     restart: unless-stopped
+    healthcheck:
       test: bash -c "if mongo --eval 'quit(db.runCommand({ ping':' 1 }).ok ? 0 ':' 2)'; then exit 0; fi; exit 1;"
     networks:
       bbb-net: