fix(chatterbox): pin omegaconf>=2.0 to prevent resolver backtracking

Without an upper-floor pin, pip's resolver backtracks through omegaconf 1.x
sdists when installing chatterbox-tts. Old 1.x setups depend on
ruamel.yaml<0.15, whose setup.py uses Python-2-era names (Str, Bytes) and
fails to build on Python 3.10+, breaking the darwin python backend build.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Assisted-by: Claude:claude-opus-4-7 [Claude Code]