Add filter unique functionality

[apatniv]

Address the issue raised in #146

Adds a Filter unique functionality to only yield unique values.

• I have read and understood the CONTRIBUTING guidelines
• All commits in my PR conform to the commit hygiene section
• I have added relevant tests
• I have not added any dependencies

Additional context

Add any other context about the problem here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (3fe9a96) to head (a5d91e7).
Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #151   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           33        34    +1     
  Lines          609       619   +10     
=========================================
+ Hits           609       619   +10     

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[BooleanCat]

Thanks for your contribution! I've made a few minor formatting changes and added docs to the README.