Minor fix in cocktail_shaker_sort

[czgdp1807]

References to other Issues or PRs or Relevant literature

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[codecov]

Codecov Report

Merging #313 (2ab9595) into master (38e8712) will increase coverage by 0.000%.
The diff coverage is 100.000%.

@@            Coverage Diff            @@
##            master      #313   +/-   ##
=========================================
  Coverage   98.873%   98.874%           
=========================================
  Files           25        25           
  Lines         3019      3021    +2     
=========================================
+ Hits          2985      2987    +2     
  Misses          34        34           

Impacted Files	Coverage Δ
pydatastructs/linear_data_structures/algorithms.py	99.507% <100.000%> (+0.004%)	⬆️