Upgrade six to 1.16.0

This project was upgraded with external_updater.
Usage: tools/external_updater/updater.sh update external/python/six
For more info, check https://cs.android.com/android/platform/superproject/+/main:tools/external_updater/README.md

Bug: 332773142
Test: TreeHugger
Change-Id: I0a7818bc8bc27baa72137c28d0ee1bc964d853fa