Launch.py broken because of pip unsupported usage.

[fedeblock]

Importing functions from pip is not supported.

https://pip.pypa.io/en/latest/user_guide/#using-pip-from-your-program

Traceback (most recent call last):
File "launch.py", line 15, in
from pip._internal.utils.misc import get_installed_distributions
ModuleNotFoundError: No module named 'pip._internal

It may be solved using importlib_metadata instead.