Prebuilt wheels for almost every OS/architecture (except musl) are now available on PyPI, eliminating the need for a build environment.
ref: https://pypi.org/project/pyworld-prebuilt/
When using style-bert-vits2 as a library, the requirement to be able to launch it in multiple processes may not be necessary. Also, if the library is embedded and exe-ed using PyInstaller or similar, it is difficult to make pyopenjtalk_worker run in a separate process.
Therefore, we changed it so that the worker is used only when it is explicitly initialized.
