Adafruit-circuitpython-is31fl3731

Thanks to brentru for the great work!

Bump to releases to build a .mpy for CircuitPython 2.0 and later releases.

In the process of updating the guide for this driver (at https://learn.adafruit.com/micropython-hardware-charlieplex-led-matrix/overview ) I saw it was slightly experimental and unfinished (fill only hit a 4x4 matrix and was randomly turning LEDs on/off). This release swaps back to the micropython-adafruit-is31fl3731 API that has been updated to work with the current CircuitPython release (2.0). This includes support for fill, pixel brightness and blinking, and frame swaps. The in-progress / experimental code from the previous version is now available in the 'experimental' branch of this repository.

Correct the example. Thanks BorisKourt!

To use in CircuitPython, download the .mpy file and copy it to the `lib` folder on the `CIRCUITPY` drive. Or, simply install the [Adafruit driver bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).

Initial release with a PIL/pillow like interface.