Support virtual environment for python

[Ryanf55]

Request

Can we have the wiki setup work in a python virtual environment?

#358 (comment)

I'm having issues with the flake8 install hosing my ROS 2 install which has flake8 installed as a debian.

Expected behavior

python3 -m venv .venv
source .venv/bin/activate
./Spinxsetup.sh
python3 update.py --site dev

Actual behavior

python3 -m venv .venv
source .venv/bin/activate
./Spinxsetup.sh

ERROR: Can not perform a '--user' install. User site-packages are not visible in this virtualenv.

[Hwurzburg]

not sure who can work on this

[Ryanf55]

At least the issue is filed. Maybe someone will have time to solve it. I manually installed things instead of using the script so I can work in the wiki.

[khancyr]

Ok that is just a matter of removing the --user when inside a venv. Patch should be simple, can do it tonight