Fixed knn regression; Made knn regression test

[codecov-io]

Codecov Report

Merging #197 into develop will increase coverage by 2.68%. The diff coverage is 100%.

@@             Coverage Diff             @@
##           develop     #197      +/-   ##
===========================================
+ Coverage    52.39%   55.07%   +2.68%     
===========================================
  Files           35       36       +1     
  Lines         2632     2669      +37     
===========================================
+ Hits          1379     1470      +91     
+ Misses        1253     1199      -54

Impacted Files	Coverage Δ
dna/kND.py	71.13% <100%> (+55.67%)	:arrow_up:
test/test_kND.py	100% <100%> (ø)

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[bjschoenfeld]

Fix kNN