Apply the same Eigen::Vector3f change to fitting.hpp
Apply the same Eigen::Vector3f change to fitting.hpp

This seems to be unused (uninstantiated) code, and only clang complains, but not MSVC & gcc.

icyrizard/eos,patrikhuber/eos,icyrizard/eos,icyrizard/eos,patrikhuber/eos,patrikhuber/eos