The locale for Azure TTS SSML was being extracted with `split("-")[:1]`,
which only takes the first segment (e.g., "en" from "en-US"). The
xml:lang attribute in SSML requires a full locale like "en-US", not just
a language code. This caused Azure TTS to either fail or use incorrect
pronunciation rules.
Changed `[:1]` to `[:2]` to properly extract the locale (e.g., "en-US").
Co-authored-by: gambletan <ethanchang32@gmail.com>
