The current guidance for install Python packages is to use
python -m pip install <package_name>
Instead of
pip install <package_name>
This ensures that one is using the version of pip that is tied to the
environment's interpreter (and, thusly, its packages). This has [been
endorsed by a core
maintainer](https://snarky.ca/why-you-should-use-python-m-pip/) as
being the recommended way to invoke pip.
As there currently are a few places where the old invocation was used,
attempt to bring them in line.
Fixes#14234
d9c7adc64c
