allow to set retry count for connect()

[vladak]

Similar to #112, it would be nice to be able to set the retry count for connect(). Currently it is hard coded to 5:

Adafruit_CircuitPython_MiniMQTT/adafruit_minimqtt/adafruit_minimqtt.py

Lines 254 to 255 in 67e0ade

	retry_count = 0
	while retry_count < 5 and sock is None:

[tekktrik]

You could submit a PR with a similar fix as before, if you're up for it!