remove minimqtt dep, its not dep.

Author: brentru

README.rst

@@ -22,7 +22,6 @@ Dependencies
 This driver depends on:
 
 * `Adafruit CircuitPython <https://github.com/adafruit/circuitpython>`_
-* `Adafruit CircuitPython MiniMQTT <https://github.com/adafruit/Adafruit_CircuitPython_MiniMQTT>`_
 
 Please ensure that all dependencies are available on the CircuitPython filesystem.
 This is easily achieved by downloading