fix gpio read

sensors.py

@@ -28,9 +28,17 @@ class GPIOState(Sensor):
     def __init__(self, pin, transform=lambda x: 1-x):
         self.pin = pin
         self.transform = transform
+        
+        self.value = GPIO.input(self.pin)
+        self.update_time()
+
+    def update_time(self):
+        self.time = perf_counter()
 
     def read(self):
-        return self.transform(GPIO.input(self.pin))
+        self.value = GPIO.input(self.pin)
+        
+        return (self.time, self.transform(self.value))
 
 class Temperature1W(Sensor):
     def __init__(self, address):