mkvenv: mark command as required

This is only available in Python 3.7+.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20230511035435.734312-26-jsnow@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed