[3.9] bpo-43993: Update vendored pip to 21.1.1 (GH-25761).#25782

Merged

pfmoore merged 1 commit intopython:3.9from

sbidoul:backport-bf99b71-3.9

May 1, 2021

Commits on May 1, 2021

[3.9] bpo-43993: Update vendored pip to 21.1.1 (GH-25761).
sbidoul
committed