To prepare fishtest for the testing of the NNUE evaluation, a worker update on fishtest was necessary and has been implemented. In most cases, this update should be automatic.
Two changes could affect contributors:
* custom_make.txt has been removed, to allow for a more appropriate architecture selection. If your use of custom_make.txt was essentially equivalent to
make ARCH=x86-64-bmi2 profile-build
* NNUE requires the compiler (g++) to be sufficiently recent and to support c++17. At least gcc 7.5.0 is needed, more recent recommended.