Added Black formatting badge

Author: evaherrada

README.rst

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     :target: https://github.com/adafruit/Adafruit_CircuitPython_MLX90614/actions/
     :alt: Build Status
 
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 CircuitPython module for the Melexis MLX90614 Contact-less Infrared Temperature sensor.  See
 examples/mlx90614_simpletest.py for a demo of the usage.