mps-youtube bug and fix

by

mps-youtube is giving errors about apt_key.

Short-term fix is to do the following.

1. delete ~/.config/mps-youtube/cache_py*
2. Open mps-youtube and type

set api_key AIzaSyApOW6Ur8oRM_1OACkkhxnNrbtv0e4qfaM

3. quit mps-youtube
4. Start mps-youtube