Support postgres date range fields

[berinhard]

Currently model bakery does not support postgres' range fields DateRangeField and DatetimeRangeField.

In #80 I've added support to the numeric range fields, but the date/datetime ones are still missing.

Expected behavior

Model bakery should create random values for models with fields as django.contrib.postgres.fields.DateRangeField or django.contrib.postgres.fields.DatetimeRangeField.

Actual behavior

The following error is being raised:

TypeError: <class 'django.contrib.postgres.fields.ranges.DateRangeField'> is not supported by baker.

Reproduction Steps

How to reproduce this issue.

1. Add DateRangeField and DatetimeRangeField as new fields in our test model;
2. The tests will start to fail with the given TypeError exception;

Versions

Python: 3.8
Django: 3.0
Model Bakery: 1.1.0