ix: migrate from kitsu.io to kitsu.app

The [kitsu.io](https://kitsu.io) domain has expired, and the main developers
do not have access to that domain. So they
[migrated](hummingbird-me/kitsu-server#1556)
to the new [kitsu.app](https://kitsu.app) domain.

This commit updates all references of `kitsu.io` to `kitsu.app`.

app/src/main/kotlin/org/koitharu/kotatsu/scrobbling/kitsu/data/KitsuRepository.kt

@@ -28,7 +28,7 @@ import org.koitharu.kotatsu.scrobbling.common.domain.model.ScrobblerService
 import org.koitharu.kotatsu.scrobbling.common.domain.model.ScrobblerUser
 import org.koitharu.kotatsu.scrobbling.kitsu.data.KitsuInterceptor.Companion.VND_JSON
 
-private const val BASE_WEB_URL = "https://kitsu.io"
+private const val BASE_WEB_URL = "https://kitsu.app"
 
 class KitsuRepository(
 	@ApplicationContext context: Context,