Removes functional from 2ndary deps in CMake subdir test

[anarthal]

Removes Boost.Functional from the CMake add_subdirectory test.
This library is no longer a secondary dependency due to an update in Fusion

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.16%. Comparing base (4558bb4) to head (de37845).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #508   +/-   ##
========================================
  Coverage    99.16%   99.16%           
========================================
  Files          145      145           
  Lines         7387     7387           
========================================
  Hits          7325     7325           
  Misses          62       62           

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