latest local should skip python virtualenvs

[Rémi Alvergnat]

toilal@toilal-ubuntu:~$ pyenv latest local 3.7
Latest version is '3.7.3/envs/3.7.3-nodeenv'
(3.7.3/envs/3.7.3-nodeenv) toilal@toilal-ubuntu:~$

I would expect to select the raw 3.7.3, not a virtualenv.

toilal@toilal-ubuntu:~$ pyenv latest local 3.7.3
Latest version is '3.7.3'
toilal@toilal-ubuntu:~$

[momo-lab]

Fix #5 . Thanks!