Leaflet Warning when a layer is removed from map

[AliyanH]

This is occurring due to the use of off() function here:
https://github.com/Maps4HTML/Web-Map-Custom-Element/blob/abff1aa1ddbb849ae6e69a30f124c4fe76178e0e/src/layer.js#L305-L306

This is because of the upgrade to leaflet 1.9.3 and the change to the use of the off function from leaflet 1.71 to 1.9.3.