Tries to find and activate a virtual environment either in the current directory or the closest one in the hierarchy.
Example:
- in
/foo/bar/baz
- first, checks if
/foo/bar/baz/venv/bin/activate
is found (and uses that if it is) - next, tries
/foo/bar/venv/bin/activate
- after that,
/foo/venv/bin/activate