Adding sbd distance method and its test.

[avilchess]

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Description

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Tests

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  1. Subject is separated from body by a blank line
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[codecov]

Codecov Report

Merging #40 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #40      +/-   ##
==========================================
+ Coverage   94.45%   94.47%   +0.02%     
==========================================
  Files          13       13              
  Lines         847      851       +4     
==========================================
+ Hits          800      804       +4     
  Misses         47       47

Flag	Coverage Δ
#Linux	93.18% <100%> (+0.03%)	⬆️
#MacOS	92.94% <100%> (+0.03%)	⬆️
#Windows	94.12% <100%> (+0.02%)	⬆️

Impacted Files	Coverage Δ
khiva/distances.py	100% <100%> (ø)	⬆️

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[otorreno]

LGTM

[otorreno]

remove this empty line