dh_virtualenv: specify python version  (#165)
dh_virtualenv: specify python version  (#165)

* Specify python version for dh_virtualenv

* Fixup missing key

* revert unrelated white space change

Co-authored-by: Dirk Thomas <19795c8185177e940eedd30ceb2b716a54a3d5dc@users.noreply.github.com>
astraw/stdeb,astraw/stdeb,astraw/stdeb