Changes: https://github.com/adafruit/Adafruit_CircuitPython_PM25/compare/2.1.15...2.1.16
To use in CircuitPython, simply install the [Adafruit CircuitPython Bundle](https://circuitpython.org/libraries).
To use in CPython, `pip3 install adafruit-circuitpython-pm25`.
Read the [docs](https://circuitpython.readthedocs.io/projects/pm25/en/latest/) for info on how to use it.