BOM-2247: Upgrade pip to 21.1.2

[mzulqarnain1]

All services are using the latest pip-tools version now which is compatible with the latest version of pip according to this compatibility chart https://github.com/jazzband/pip-tools/#versions-and-compatibility

Sandbox configured successfully with changes for all services here https://tools-edx-jenkins.edx.org/job/sandboxes/job/CreateSandbox/

More details on https://openedx.atlassian.net/browse/BOM-2247