fix deploy script

Author: Brooooooklyn

Makefile

@@ -3,4 +3,4 @@ format:
 
 release:
 	python setup.py sdist bdist_wheel
-	twine upload --repository-url https://upload.pypi.org/legacy/ dist/* -u $PYPI_USERNAME -p $PYPI_PASSWORD
+	twine upload --repository-url https://upload.pypi.org/legacy/ dist/* -u ${PYPI_USERNAME} -p ${PYPI_PASSWORD}