remove virtual from the add_measurement method (backport #2558)

[mergify]

Fixes: #2556

I don't think the method needs to be virtual, and with this change the warnings shouldn't appear anymore.

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This is an automatic backport of pull request #2558 done by Mergify.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.06%. Comparing base (638ea8e) to head (d032a4d).
⚠️ Report is 3 commits behind head on jazzy.

Additional details and impacted files

@@            Coverage Diff             @@
##            jazzy    #2562      +/-   ##
==========================================
+ Coverage   89.01%   89.06%   +0.04%     
==========================================
  Files         145      145              
  Lines       16535    16534       -1     
  Branches     1396     1396              
==========================================
+ Hits        14719    14726       +7     
+ Misses       1283     1277       -6     
+ Partials      533      531       -2     

Flag	Coverage Δ
unittests	89.06% <100.00%> (+0.04%)	⬆️

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Files with missing lines	Coverage Δ
...lude/hardware_interface/types/statistics_types.hpp	96.62% <100.00%> (+1.12%)	⬆️

... and 3 files with indirect coverage changes

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