Django-pivot

Minor fixes to support Django 4

Fix capitalization of Readme in setup.py

Added support for default values. You can specify a default value for a columns where no data is found, and you can have rows filled in with all default values by specifying your target rows.

Add support for multi-level pivot tables. It's now possible to pass a list to the `rows` parameter to get results where the rows are grouped by more than one column. E.g,

>>> pivot_table = pivot(ShirtSales, ['region', 'gender'], 'shipped', 'units')

To see the sum of units on each shipped date grouped by both region and gender.

Add the ability to change the row keys by passing a function that transforms a string.

Pivot tables now give you access to the descriptive text defined in choices.