fix: Install pip and pip-tools in upgrade script

[edx-requirements-bot]

Additional information from script execution

Python code cleanup by the cleanup-python-code Jenkins job.

This pull request was generated by the cleanup-python-code Jenkins job, which ran

echo "-c constraints.txt
# Core dependencies for installing other packages

pip
setuptools
wheel
" >>  requirements/pip.in;
pip-compile --allow-unsafe --rebuild --upgrade -o requirements/pip.txt requirements/pip.in;

The following packages were installed:
pip-tools

Deleted obsolete pull_requests:
#879