Remove Context::get_voice_regions
Remove Context::get_voice_regions

This was basically an alias to http::get_voice_regions and likely had
no use case.

Flat/serenity,eLunate/serenity,zeyla/serenity,acdenisSK/serenity,zeyla/serenity.rs,Roughsketch/serenity,Lakelezz/serenity