Change mds_api_url for nextbike

[itnextbike]

Dear MDS contributors,

there has been a change regarding the api url of nextbike. Could you please update this field in the providers.csv?

mds_api_url - https://mds-provider-api.nextbike.net

Thank you!
Inga Traub - Software Developer @ nextbike

[schnuerle]

Thanks we will work this into the next release. If you need it in the dev branch sooner you can make a PR.