Fix pre-release of keras installing

[cabrust]

We typically use setup.py develop to install dependencies, however this sometimes pulls pre-releases. Currently, it installs keras==2.7rc0 which is broken. This PR switches everything to pip install -e ., which is also used in the test cases, and also fixes the Python version specs in the actions to avoid confusion later on.

[codecov-commenter]

Codecov Report

Merging #58 (383e8ec) into main (2ad4b90) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #58   +/-   ##
=======================================
  Coverage   65.50%   65.50%           
=======================================
  Files          79       79           
  Lines        3180     3183    +3     
  Branches      494      494           
=======================================
+ Hits         2083     2085    +2     
- Misses       1010     1011    +1     
  Partials       87       87           

Impacted Files	Coverage Δ
chia/helpers/ioqueue.py	19.64% <0.00%> (-0.36%)	⬇️
chia/helpers/better_ioqueue.py	79.68% <0.00%> (+0.65%)	⬆️

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