Pressure vessel doesn't support games in /usr/local

A user has reported pressure-vessel-launch[7045]: Failed to start command: Failed to change to directory '/usr/local/games/SteamLibrary/steamapps/common/Streets Of Kamurocho' (Datei oder Verzeichnis nicht gefunden) at https://github.com/ValveSoftware/Proton/issues/4289#issuecomment-713618064.

Looks like something fairly straight forward to check.

Reference: https://github.com/ValveSoftware/steam-runtime/issues/288