Fix compatibility with Python version >= 3.8.4
In Python 3.8.4 and upwards it is no longer allowed to have constants "True", "False" and "None" within a ast.Name node. See bpo-40870 description at: https://docs.python.org/3/whatsnew/changelog.html
The issue was found when running test/test-menu-rules.py with Python 3.8.5