Fix installation issue

[hndgzkn]

I do not have a clear idea why installation started to give error, but this fixes the issue.

This will also make CI pass for #42 and #44.

[codecov]

Codecov Report

Merging #45 (c567862) into main (ad30e87) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #45   +/-   ##
=======================================
  Coverage   74.50%   74.50%           
=======================================
  Files          43       43           
  Lines        2593     2593           
=======================================
  Hits         1932     1932           
  Misses        661      661           

Flag	Coverage Δ
unittests	74.50% <ø> (ø)

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[agramfort]

removing setup.py ???

…

[hndgzkn]

We can keep it, however it was already empty. I did not completely read PEP517/518, but from alphacsc/alphacsc#47 I understand that removing setup.py complies with the conventions.

removing setup.py ???

[agramfort]

I use setup.py files for all my projects but I am open to anything that works. I still see people do things like: python setup.py install or python setup.py develop

[hndgzkn]

We can keep the file if you prefer so. I just removed considering PEP conventions and as it didn't contain any specific code.

The problem is fixed even if setup.py is there, I just needed to remove the imports.

[tomMoral]

I think we cannot remove the setup.py because else the pip install -e . does not work anymore?
I also updated the sphinx-version as done by @hndgzkn in alphacsc/alphacsc#44