Webhooks should work with something like here:
<service name="webhook">
<param name="repourl">https://github.com/sailfishos/gst-plugins-base.git</param>
<param name="branch">master</param>
</service>
And configure https://webhook.sailfishos.org/webhook/ as git-hub/lab/berg hook.
See @lbt’s explanation here Community OBS - Refurbished and re-floated - #22 by lbt
Maybe the https://webhook.sailfishos.org/webhook does not work anymore (as build.sailfishos.org doesn’t now, either), and you need to set it up as https://webhook.merproject.org/webhook :-S 