added keyboard interupt handling

main.py

@@ -28,7 +28,8 @@ ntfy_token = os.environ['NTFY_Token']
 device_name = os.environ['device_name']
 shutdown_timer = int(os.environ['shutdown_timer'])
 
-with serial.Serial(device_name, 115200, timeout=1) as ser:
+try:
+    with serial.Serial(device_name, 115200, timeout=1) as ser:
         inverter_offline_counter = 0
         while True:
             if ser.readline().decode().strip() == "0":
@@ -48,3 +49,6 @@ with serial.Serial(device_name, 115200, timeout=1) as ser:
                         }
                     )
         os.system("shutdown now")
+except KeyboardInterrupt:
+    logger.info("Exiting gracefully")
+    exit()