Allow specifying Python version for virtual environment creation

make-venv.sh

@@ -1,6 +1,8 @@
 #! /usr/bin/env bash
 
-python3 -m venv .venv
+VERSION="${1:-3}"
+
+python${VERSION} -m venv .venv
 ./.venv/bin/pip install --upgrade pip
 ./.venv/bin/pip install -r requirements.txt