add `make venv` to create the virtual environment

Makefile

-.PHONY: install uninstall
+.PHONY: install uninstall venv
 
 install:
 	cp src/main.py ~/.local/bin/gplt
@@ -15,3 +15,6 @@ uninstall:
 	rm ~/.local/bin/multi_bar.py
 	rm ~/.local/bin/error.py
 	rm ~/.local/bin/log.py
+
+venv:
+	./scripts/create-venv.sh ~/.local/share/venvs

scripts/create-venv.sh

+#!/usr/bin/env bash
+
+[[ -z $1 ]] && {
+    echo "please give the path to the venv directory"
+    exit 1
+}
+
+virtualenv "$1/gplt" --prompt gplt
+source "$1/gplt/bin/activate"
+pip install -r requirements.txt