Fix OSError by replacing os.link with os.symlink for cross-drive compatibility

[cary-rowen]

Link to issue number:

None

Summary of the issue:

The os.link function was causing an OSError when attempting to create a hard link between different drives, preventing invoke run and invoke bench from executing properly.

Description of how this pull request fixes the issue:

This pull request replaces the os.link function with os.symlink in the bookworm/platforms/win32/speech_engines/piper/__init__.py file. Unlike hard links, symbolic links can span across different drives, resolving the issue and allowing the commands to execute without errors.

Testing performed:

Tested in an environment with the project directory and Python installation on separate drives. Verified that invoke run and invoke bench commands now execute successfully without encountering the OSError.

Known issues with pull request:

None