wordclock-dimmer: Make logging less verbose

The time is already stored in the journal, so it does not need to be
logged. Only logging changed values makes the log less polluted once a
fixed value has been reached ((3, 3, 3) or (3, 0, 0)):

pkgs/wordclock-dimmer/wordclock-dimmer.py

@@ -61,15 +61,6 @@ def get_color_for_time(time: datetime.time, base=(60, 60, 60)) -> (int, int, int
         )
 
 
-def update(client: mqtt.Client):
-    time = datetime.datetime.now().time()
-    color = get_color_for_time(time)
-    print(f"{time}: setting color to {color}")
-    sys.stdout.flush()
-    set_color(client, *color)
-    pass
-
-
 client = mqtt.Client("wordclock.py")
 
 user = os.environ["WORDCLOCK_MQTT_USER"]
@@ -83,6 +74,15 @@ host = os.environ["WORDCLOCK_MQTT_HOST"]
 client.username_pw_set(user, password)
 client.connect(host, 1883, 60)
 
+color = (0, 0, 0)
+
 while True:
-    update(client)
+    time = datetime.datetime.now().time()
+    new_color = get_color_for_time(time)
+    if new_color != color:
+        color = new_color
+        print(f"setting color to {color}")
+        sys.stdout.flush()
+        set_color(client, *color)
+
     sleep(300)