Request to add an open-source license (preferably Apache-2.0)

Hi, thank you for creating and sharing this package. It is currently used as a dependency in the [ESPnet](https://github.com/espnet/espnet) project (Apache-2.0 licensed).
However, this repository has no LICENSE file, and the PyPI metadata shows License: UNKNOWN. Under copyright law, this defaults to "All Rights Reserved", which creates a license compliance risk for ESPnet and its users.
Given that this package hasn't been updated in several years, I understand you may no longer be actively maintaining it. Would you consider adding a permissive open-source license? Apache-2.0 would be ideal for compatibility with ESPnet, but MIT, BSD-2-Clause, or BSD-3-Clause would also be perfectly acceptable.
If you're unable to add a license, could you please confirm whether this code was intended to be open-source? Any clarification would help the ESPnet community determine next steps.
Thank you for your time and contribution!

Check the repository root to confirm that LICENSE is absent, then inspect the PyPI metadata showing License: UNKNOWN. The copyright holder must confirm whether the project may be open-sourced and select an acceptable license; this is done when an authorized license is added and the package metadata reflects it.

Written by the indexing model from the issue text.