Fix most entries that are currently not loading

[stefan9999991]

Most entries in the app haven't been loading for a few weeks. I investigated and this is because the Jikan api currently has some problems. The issues that I identified that I could solve were that the Xamarin HttpClient negotiated HTTP/2.0 while Jikan doesn't support that, and that without a specific Accept-Encoding string, most requests received a 504 Gateway Timeout error. I fixed both issues in JikanDotNet (the library we use to interface with the API) and opened an upstream PR, and pointed the dependency source in this project to that fork.

You can verify the changes in the package by going to the fork. I published the package through github actions (not manually) so the published binary can be traced directly back to that exact source with no manual build step in between.

This includes a new nuget.config pointing at that package's feed. This is meant to be temporary — once the upstream PR is merged and a new official release is published, we should revert to the standard NuGet package. This fixed most entries, but not all which was quite annoying, so I changed the api used for retrieving anime entry data to the official mal api so all entries succeeded. Tested locally: previously-failing entries (e.g. "Fire Force" ID 38671) now load reliably. Note that Jikan's API itself still appears to have some ongoing stability issues independent of this fix, so occasional failures may still occur, but this significantly improves reliability for the other functions that still rely on it.

I also changed the api used for retrieving seasonal data to the official MAL api, so the season tab loads again. Since Jikan is having so much trouble, and MAL has an api again, it might be worth considering moving some of the api calls from Jikan to MAL. This would not be possible for all, since for example the MAL api doesn't expose an endpoint that gives episode information (titles and stuff).