For a minor update (3.5.0 → 3.5.1 or more in general, where only changes zin x.y.z), you do not need to do anything.
Virtualenv in a subdirectory binhas a symbolic link to the Python executable as follows:
python -> python3.5
python3 -> python3.5
python3.5 -> /usr/bin/python3.5
/usr/bin/python3.5 3.5.0 3.5.1, virtualenv Python.
(x y x.y.z), virtualenv.
pyvenv ( Python 3.3), --upgrade:
, Python, , Python .
... . , pyvenv python3 -m venv Python 3.6.
virtualenv, , - virtualenv Python, pip install -r requirements.txt.
, requirements.txt . , , virtualenv, pip freeze --local > requirements.txt Python virtualenv.