Supergraph listenaddr is not updated although hot-reload is enabled

STRs:

start a router with `--hot-reload` enabled and this configuration
```yaml
supergraph:
  listen: 127.0.0.1:4000
```

replace the configuration with


```yaml
supergraph:
  listen: 127.0.0.1:4010
```

Expected: the router now listens to 127.0.0.1:4010
Actual: the router still listens to 127.0.0.1:4000