Description of problem:
The version 1.12.4 of the visvis Python module is not compatible with Python 3.9 and will crash applications even just importing it. 


Version-Release number of selected component (if applicable):
1.12.4-2


How reproducible:
Always


Steps to Reproduce:
1. Launch python3 shell on FC34
2. Import visvis module


Actual results:
Python 3.9.4 (default, Apr  6 2021, 00:00:00) 
[GCC 11.0.1 20210324 (Red Hat 11.0.1-0)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import visvis
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.9/site-packages/visvis/__init__.py", line 55, in <module>
    from visvis.core import *
  File "/usr/lib/python3.9/site-packages/visvis/core/__init__.py", line 30, in <module>
    from visvis.core.constants import *
  File "/usr/lib/python3.9/site-packages/visvis/core/constants.py", line 162, in <module>
    colormaps['magma'] = np.frombuffer(base64.decodestring(_magma), np.float32).reshape(256, 3)
AttributeError: module 'base64' has no attribute 'decodestring'


Expected results:
Normal import of module


Additional info:
In Python 3.9 decodestring should be replaced with decodebytes.
Problem has been already solved upstream: https://github.com/almarklein/visvis/pull/117/commits/aff691786457213e2f7d6dd33452306693d74249

Either bump therefore to a more recent version or selectively apply some patches.