Reworded error message

[jminor]

This PR changes an error message which was flagged here: https://security.lfx.linuxfoundation.org/#/a092M00001If9uZQAR/non-inclusive-language

[codecov-commenter]

Codecov Report

Merging #1482 (3ac3da9) into main (b6fbca2) will increase coverage by 0.08%.
The diff coverage is 0.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1482      +/-   ##
==========================================
+ Coverage   78.89%   78.97%   +0.08%     
==========================================
  Files         200      200              
  Lines       21724    21779      +55     
  Branches     4403     4406       +3     
==========================================
+ Hits        17139    17200      +61     
+ Misses       2355     2350       -5     
+ Partials     2230     2229       -1     

Flag	Coverage Δ
py-unittests	78.97% <0.00%> (+0.08%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...entimelineio-bindings/otio_serializableObjects.cpp	26.59% <0.00%> (ø)
tests/test_cmx_3600_adapter.py	99.59% <0.00%> (+0.02%)	⬆️
src/opentimelineio/serialization.cpp	47.99% <0.00%> (+0.18%)	⬆️
...opentimelineio/opentimelineio/adapters/cmx_3600.py	85.06% <0.00%> (+0.28%)	⬆️
tests/test_plugin_detection.py	91.46% <0.00%> (+0.67%)	⬆️
...-opentimelineio/opentimelineio/plugins/manifest.py	91.50% <0.00%> (+4.36%)	⬆️

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