Since pip v22, python3.6 is not supported (the minimum version is
python3.7). This patch adds the reference for the pip3.6 URL to be
used instead of the default one.
Closes-Bug: #1959600
Change-Id: Iab2c391d5388461fe9e9037cee81884ce8032e72
(cherry picked from commit a756f4b968)