Please consider switch to standard json module
#### Problem description

The ujson we currently using is not well maintained, no activity and no response since last two years:
https://github.com/esnme/ultrajson/issues/291
and other projects are switching out of it:
https://github.com/fastavro/fastavro/issues/150
It makes it hard for us to handle new feature requests:
https://github.com/pandas-dev/pandas/issues/12213
and has bugs causing us unable to consume standard JSON files:
https://github.com/esnme/ultrajson/issues/252
