Update virtualenv to 20.16.4#1970

pyup-bot wants to merge 1 commit intomasterkragniz/python-etcd3:masterfrom

pyup-update-virtualenv-20.4.6-to-20.16.4kragniz/python-etcd3:pyup-update-virtualenv-20.4.6-to-20.16.4Copy head branch name to clipboard