2.4.0-pre.1

This updates the default model to the faster and better Turbo 2.5, and adds support for legacy voices.

What's Changed

• Add support for legacy voices by @carleeno in #141
• Update default model to Turbo 2.5 and add languages by @carleeno in #142

Full Changelog: 2.3.1...2.4.0-pre.1