Remove unused variable from fireflies

It seems the `bright_div` variable is not used.

examples/fireflies.py

@@ -2,7 +2,6 @@ import time
 import ws2812b
 import random
 
-bright_div = 20
 numpix = 50  # Number of NeoPixels
 # Pin where NeoPixels are connected
 strip = ws2812b.ws2812b(numpix, 0,0)
@@ -51,4 +50,4 @@ while True:
         flashing[i][3] = flashing[i][3] + flashing[i][4]
         time.sleep(0.005)
             
- 
+