Unable to pass multiple apps alerts through from alertmanager

[nusnewob]

I'm trying to setup alertmanager to forward multiple apps errors to Sentry, therefore the webhook url needs to be dynamic, I'm exposing .Labels.sentry_io_app as Sentry <project_id>, see configs below.
However, Alertmanager webhook url parameter doesn't support using template syntax (see issue). Is there any other way to pass <project_id> to the gateway?

Example config

receivers:
- name: team
  webhook_configs:
  - url: 'http://127.0.0.1:9096/{{ .Labels.sentry_io_app }}'
    send_resolved: false