Remove unused header

[mborland]

We don't depend on fp_traits here.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.29%. Comparing base (0d868fd) to head (3e13f12).
⚠️ Report is 2 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1353   +/-   ##
========================================
  Coverage    95.29%   95.29%           
========================================
  Files          814      814           
  Lines        67467    67467           
========================================
  Hits         64294    64294           
  Misses        3173     3173           

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