Adafruit-circuitpython-ds3231

Thanks to brentru for the great work!

Now with less lint, including a fix to the example. Thanks mrmcwethy !

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases) or the zip from here that matches the version of CircuitPython you are using.

Read the [docs](https://circuitpython.readthedocs.io/projects/ds3231/en/latest/README.html) for info and examples.

Changes made to follow changes in Adafruit_Circuitpyton_BusDevice.I2CDevice

New release to generate mpy binary for CircuitPython 2.x (note this might not work with CircuitPython 3.0+). No functional changes to code.

Thanks hukuzatuna and tannewt !