Add benchmarks

[JSorngard]

This PR adds some benchmarks that can be used to test the crate

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.89%. Comparing base (f36f1af) to head (49f1798).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #66   +/-   ##
=======================================
  Coverage   74.89%   74.89%           
=======================================
  Files           1        1           
  Lines         490      490           
=======================================
  Hits          367      367           
  Misses        123      123           

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[JSorngard]

Turns out criterion needs a much later Rust version, and cargo-msrv flags the need of the dev-dependencies as well, so this would increase the MSRV of the crate.