mapbox new token

[Derryrover]

We need to change the the mapbox acces token for the background layers.

Here is the pr:
#44

What url is this app running on?
If it is not on one of the lizard.net domains we may need to add it to the whitelisted urls in the mapbox-admin-dashboard.
Please notify Tom de Boer in that case.

This ticket is part of a bgger ticket to change all mapbox tokens for all our apps:
nens/threedi-live-site#476