Rotate text by 180°, so you can sı̣ɥʇ ǝʞı̣ן ǝʇı̣ɹʍ.

pip install textflip

>>> from textflip import flip
>>> flip("Testing textflip")
'dı̣ןɟʇxǝʇ ɓuı̣ʇsǝ┴'

Not every letter has a perfect flipped counterpart, so many letters just don't work or look slightly weird upside-down. Most western letters work somewhat fine, though.