Upgrade: misc pip upgrades 2020-08: SymPy, pip, six #30425
Description
Upgrade a bunch of pip packages to increase the shelf life of Sage 9.2
- sympy 1.6.2 - https://github.com/sympy/sympy/wiki/Release-Notes
- six 1.15.0
- pip 20.2.3
Depends on #30317
CC: @jhpalmieri
Component: packages: standard
Keywords: upgrade
Author: Matthias Koeppe
Branch: c9ef539
Reviewer: John Palmieri
Issue created by migration from https://trac.sagemath.org/ticket/30425