audio.cpp 0.4 adds Higgs Audio v3 TTS 4B and Fish Audio S2 Pro

New release of audio.cpp, a C++/GGML audio library, adds support for Higgs Audio v3 TTS 4B (10x real-time) and Fish Audio S2 Pro, plus full GGUF loading and Q8 optimizations. The update brings high-quality TTS to local inference with improved performance.