TrafficSinkAction: If Rate is omitted, a (false) warning is raised that it is not `inf`

In https://www.asam.net/static_downloads/ASAM_OpenSCENARIO_V1.2.0_Model_Documentation/modelDocumentation/content/TrafficSinkAction.html, the property rate is optional and if omitted, it should be interpreted as inf.

Yet, if the Rate is omitted, OSE raises a warning, that rate is not set to inf.