add blue led toggle script and new dependencies

src/scripts/blink_led.py

@@ -0,0 +1,17 @@
+#!/usr/bin/env python3
+import time
+import RPi.GPIO as GPIO
+
+GPIO_PIN = 12
+
+GPIO.setmode(GPIO.BCM)
+GPIO.setup(GPIO_PIN, GPIO.OUT)
+
+while True:
+    print("toggle led ON")
+    GPIO.output(GPIO_PIN, GPIO.HIGH)
+    time.sleep(1)
+    print("toggle led ON")
+    GPIO.output(GPIO_PIN, GPIO.LOW)
+    time.sleep(1)
+