schemas: partial revert of f2fb4843aebe2bd45e276758e17eaf071024bb58
schemas: partial revert of f2fb4843aebe2bd45e276758e17eaf071024bb58

The idea was to prevent people from creating taxis the hard way, but it
seems I just broke the API for historical partners already doing it
wrong.

The creation of TaxiPOSTSchema and TaxiPUTSchema should have been the
only answer, TaxiSchema is already exposed by Swagger on GET only,
"dump_only" wasn't bringing more except trouble.

openmaraude/APITaxi,openmaraude/APITaxi