Update ujson dependency

[n1lsB]

Hello,

within a Pretix deployment in our team, we had issues with incompatible versions of ujson and drf_ujson.

This library (drf_ujson2) uses the default parameter from ujson in renderers.py#L44. This parameter is introduced in version 4.2.0 of ujson. However, drf_ujson2 only enforces ujson>=2.0.1 as dependency.

From my point of view, we should change this dependency to at least ujson>=4.2.0. Are there any objections against this proposal?

[Amertz08]

Thanks for bringing this up. I will dig into the changes and see what needs to happen.