Adafruit-circuitpython-rtttl

* Fixed the library so multiple calls to `play` work as expected and don't get a "Pin in use" exception.

Documentation is available [on ReadTheDocs](https://circuitpython.readthedocs.io/projects/rtttl/en/latest/).

To use, simply load the [Adafruit CircuitPython Library Bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases) or download the corresponding file from this release.

Thanks to tannewt for the great work!

To use, simply load the [Adafruit CircuitPython Library Bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases) or download the correct file from this release.

Thanks to brentru for the great work!

Example playing two songs

Play some RTTTL tunes with this library!