Pip doesn't install tflite-runtime from dependency link

Pip doesn't find tflite-runtime from the dependency link in setup.py

This only affects armv7l devices which includes the Raspberry Pi

as a work around you can run:

```sh
pip3 install https://dl.google.com/coral/python/tflite_runtime-2.1.0.post1-cp37-cp37m-linux_armv7l.whl
```

