[BB-6453] Bump pip-tools
The CI process was broken due to pip and pip-tools being incompatible.
It seems the docker image for python:3.8 just got upgraded to 3.8.13 and pip to 22.0.4 which is incompatible with pip-tools 6.4.0
This MR bumps pip-tools to 6.7.0 which is compatible.
Edited by Paulo Viadanna