Updates hardware_system test_mux

hardware_system.py

@@ -67,7 +67,7 @@ class OhmPiHardware:
         for _, mux in self.mux_boards.items():
             mux.barrier = self.mux_barrier
             for k, v in mux.cabling.items():
-                update_dict(self._cabling, (mux_id, k[0]))
+                update_dict(self._cabling, {k: (mux_id, k[0])})
         print(self._cabling)
         self.readings = np.array([])  # time series of acquired data
         self._start_time = None  # time of the beginning of a readings acquisition