decodestring has been deprecated and removed in favor of decodebytes in Python 3.9

[tirkarthi]

Use decodestring in Python 2 and decodebytes in Python 3. Reference : python/cpython#18022

Caliopen/src/backend/interfaces/REST/py.server/caliopen_api/user/authentication.py

Line 48 in 51c8893

auth = base64.decodestring(authorization[1])

Caliopen/src/backend/interfaces/REST/py.server/caliopen_api/user/authentication.py

Line 118 in 51c8893

b64_header = base64.decodestring(sign_header)