Fix numpy deprecation issues

[kdiers]

From the numpy deprecation message (the same holds for np.int):

np.float was a deprecated alias for the builtin float. To avoid this error in existing code, use float by itself. Doing this will not modify any behavior and is safe. If you specifically wanted the numpy scalar type, use np.float64 here.

As a consequence, all occurences of np.float / np.int have been replaced with float / int.

[codecov-commenter]

Codecov Report

Merging #28 (d54accf) into main (1807c3c) will not change coverage.
The diff coverage is 0.00%.

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@@          Coverage Diff          @@
##            main     #28   +/-   ##
=====================================
  Coverage   5.29%   5.29%           
=====================================
  Files         14      14           
  Lines       2359    2359           
  Branches     306     306           
=====================================
  Hits         125     125           
  Misses      2231    2231           
  Partials       3       3           

Flag	Coverage Δ
unittests	5.29% <0.00%> (ø)

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Impacted Files	Coverage Δ
lapy/func_io.py	0.00% <0.00%> (ø)

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