Tiny Cloud and local services text-to-speech integration module.
For cloud versions - most likely you would be better served by official modules:
gcp:cloud.google.com/go/texttospeech/apiv1acs:github.com/Microsoft/cognitive-services-speech-sdk-go
Add module to your project: go get github.com/beauxarts/tts-integration.
This package defines a common Synthesizer interface (source), that is realized with gcp (Google Cloud), acs (Azure Cognitive Services), say (macOS say command).
lego is a reference implementation of the Synthesizer and provider specifics (source).