upgrading tensorflow to 2.5.0

[scarrazza]

In this PR:

• upgrade requirement from 2.4.1 to 2.5.0
• include version checks, in order to tell the user what is wrong.
• extend python tests and wheels to python3.9
• updated readme with compatibility table.

[codecov]

Codecov Report

Merging #6 (f9c584b) into main (fe67ca9) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main        #6   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            4         3    -1     
  Lines          371       371           
=========================================
  Hits           371       371           

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...m_operators/python/ops/qibo_tf_custom_operators.py	100.00% <100.00%> (ø)

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[stavros11]

Thanks for the update, looks good. Just one comment below:

Also noting that I have not been able to install tf2.5 on my local machine yet. After upgrading with pip, when I try to import tensorflow I get an error:

tensorflow.python.framework.errors_impl.NotFoundError: /home/stavros/.local/lib/python3.8/site-packages/tensorflow/core/kernels/libtfkernel_sobol_op.so: undefined symbol: _ZN10tensorflow6thread10ThreadPool26TransformRangeConcurrentlyExxRKSt8functionIFvxxEE

[scarrazza]

@stavros11 shall we merge this and release 0.0.2?

[stavros11]

@stavros11 shall we merge this and release 0.0.2?

I was finally able to install tf2.5 with pip in a clean environment and check. Everything seems to work both with 2.4.1 and 2.5 and I get the proper error messages if I try to use the custom operators compiled with a different version. I think we can merge.

[scarrazza]

Perfect, thanks for the confirmation.