[Bug]: Client 0.19.38 is not backward compatible due to "router" extra field

[r4victor]

Steps to reproduce

1. Use CLI 0.19.38 (or master) and server 0.19.37
2. Apply a gateway configuration
3. You'll get

Server validation error: 
{'detail': [{'loc': ['body', 'configuration', 'router'],
             'msg': 'extra fields not permitted',
             'type': 'value_error.extra'}]}

does not matter if router is specified or not.

Actual behaviour

No response

Expected behaviour

No response

dstack version

master

Server logs

Additional information

No response

[Bihan]

@r4victor. I've handled the case when router is not specified. What if router is set and the server version is 0.19.37? Should we show message like this?

"The 'router' field is not supported by this server version. Please upgrade your server to version 0.19.38 or later to use router functionality."

[r4victor]

@Bihan we don't handle this usually – the user will see that the server rejected request due to extra field present – that's sufficient.