Fix python 3.9 and 3.8 error

[josesaranda]

This MR fixes khiva-python dll location for python 3.9 version

[codecov[bot]]

Codecov Report

Merging #62 (2ed40b0) into master (891622c) will decrease coverage by 0.18%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #62      +/-   ##
==========================================
- Coverage   84.84%   84.65%   -0.19%     
==========================================
  Files          14       14              
  Lines        1597     1597              
==========================================
- Hits         1355     1352       -3     
- Misses        242      245       +3     

Flag	Coverage Δ
Linux	?
MacOS	?
Windows	84.65% <100.00%> (ø)

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Impacted Files	Coverage Δ
khiva/library.py	84.37% <100.00%> (-3.13%)	:arrow_down:

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