Update sorts/quick_sort_3_partition.py (#2507)

* Update sorts/quick_sort_3partition.py

Another quick sort algorithm, returns a new sorted list

* Update sorts/quick_sort_3_partition.py

rename quick_sort_3partition to quick_sort_3part

* Update sorts/quick_sort_3_partition.py

rename quick_sort_3part to three_way_radix_quicksort
Three-way radix quicksort:
https://en.wikipedia.org/wiki/Quicksort#Three-way_radix_quicksort
First divide the list into three parts.
Then recursively sort the "less than" and "greater than" partitions.

* Update sorts/quick_sort_3_partition.py

Co-authored-by: Christian Clauss <cclauss@me.com>

Co-authored-by: Christian Clauss <cclauss@me.com>