Changed path to lib in mux_gen.py to a relative path
Changed path to lib in mux_gen.py to a relative path

Signed-off-by: Grzegorz Latosinski <574624477ed0116ef9f8ff1ead5d9d56a6c88da6@antmicro.com>

SymbiFlow/python-symbiflow-v2x,SymbiFlow/python-symbiflow-v2x