set system limit to at least 5

jsc_custom/spawner/spawner.py

@@ -346,6 +346,7 @@ async def is_system_allowed(spawner, user_options):
         if limit > system_limit:
             system_limit = limit
     if system_limit:
+        system_limit = max(system_limit, 5)
         current = 0
         for spawner in named_spawners:
             if (