Add Allsvenskan support

Hi Joakim, Thanks for the feature request! Great news - I'm already working on adding Allsvenskan support and hoping to get it live before the season kicks off on April 4th. Swedish football has a solid following and it makes sense to include their top league in our coverage. I'll prioritize getting this ready in time for the season start, so keep an eye on the API in the coming days. Once it's live, you'll be able to access Allsvenskan data through the standard endpoints like /api/leagues/ and /api/events/. I'll make sure to update the docs when it's ready. Thanks for using BSD and suggesting this addition! - Bzzoiro