Python >= 3.9 - Replaced deprecated function

[zi0Black]

Since python 3.1 base64.decodestring is a deprecated alias of base64.decodebytes(s). In python 3.9, the function is no longer available and must be replaced.

Official documentation:

• https://docs.python.org/3.8/library/base64.html#base64.decodestring
• https://docs.python.org/3.9/library/base64.html