Whisper now needs a writable location for downloading models from
Hugging Face Hub. The default location is `~/.cache/huggingface/hub`,
but this is not writable in our container. The path can be controlled
via one of several environment variables, but we're setting `HF_HOME` as
it is sets the top level directory for several related paths.
Piper is the new text-to-speech service for Home Assistant. Whisper is
a speech-to-text service. Together, these services, which communicate
with Home Assistant via the Wyoming protocol, provide the speech
interface to the new Home Assistant Voice Assistant feature.
Dustin