As suggested when you move to ESPs. Modification of the HX711 library file will fix this. I suggested commenting out the lines in the hx711.cpp... see below. (unless you need to stay compatible with very old version of the compiler/Ardiuno).
/*
#if ARDUINO_VERSION <= 106
// "yield" is not implemented as noop in older Arduino Core releases, so let's define it.
// See also: esp8266 - What is the secret of the arduino `yield()`function? - Stack Overflow
void yield(void) {};
#endif
*/