Update cheatsheets

pyenv-virtualenv

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+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# pyenv virtualenv
+
+> Create virtual environments based on one's installed Python distributions.
+> More information: <https://github.com/pyenv/pyenv-virtualenv>.
+
+- Create a new Python 3.6.6 virtual environment:
+
+`pyenv virtualenv {{3.6.6}} {{virtualenv_name}}`
+
+- List all existing virtual environments:
+
+`pyenv virtualenvs`
+
+- Activate a virtual environment:
+
+`pyenv activate {{virtualenv_name}}`
+
+- Deactivate the virtual environment:
+
+`pyenv deactivate`