Jikan v4 support

[PolyMeilex]

Jikan v4 Public Alpha Preview is available for testing. So it's probably a good idea to start work on support for it.

WIP Documentation: https://docs.api.jikan.moe/ Alpha Preview Endpoint: https://api.jikan.moe/v4-alpha

[PolyMeilex]

Jikan v3 is going to be gone soon, so the port to v4 should happen ASAP Jikan v4 is now the default one: https://docs.api.jikan.moe/

More info about v3 deprecation: https://docs.google.com/document/d/172RQ9wWiXqOnGqjXrV3cxMNceiqwCjxjprSFuyLwQJM/edit

[PolyMeilex]

Progress so far:

• [x] Anime
• [x] Characters
• [x] Club
• [x] Genres
• [x] Magazines
• [x] Manga
• [x] People
• [x] Producers
• [x] Random
• [x] Recommendations
• [x] Reviews
• [x] Schedules
• [ ] Users
  • [x] Lists (not planed, it will get removed soon anyway)
  • [ ] Not list related user endpoints
• [x] Seasons
• [x] Top
• [x] Watch
• [ ] Unit Tests