Build breaks due to missing file: gaussianbeam.cpp/.h

[pe224]

When triggering the build process via pip by e.g.

pip install git+https://github.com/usnistgov/pySCATMECH

it fails complaining that scatmech/gaussianbeam.cpp and scatmech/gaussianbeam.h are missing.

The files are referenced in setup.py here and here.
They are not in the scatmech/ subfolder and not in the official C++ library at https://github.com/usnistgov/SCATMECH either.

Since they are not referenced anywhere else in the code, removing the respective lines from setup.py seems to fix the build.
Can this be fixed permanently?