Fix benchmark

[lostella]

• Add missing dependency
• Fix bug in benchmark problem

[codecov]

Codecov Report

Merging #49 (52886d1) into master (28f3cfc) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #49   +/-   ##
=======================================
  Coverage   87.96%   87.96%           
=======================================
  Files          18       18           
  Lines         748      748           
=======================================
  Hits          658      658           
  Misses         90       90           

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[lostella]

Benchmark workflow is failing due to missing dependency in master. Running fine with the code in this PR; merging.