Address deprecated /tracks endpoint

These changes correspond with the recommended `GET /playlists/{playlist_id}/items` call for fetching tracks.

https://developer.spotify.com/documentation/web-api/reference/get-playlists-tracks states that `GET /playlists/{playlist_id}/tracks` is deprecated.

Author: aaronskiba

src/services/trackService.ts

@@ -7,11 +7,11 @@ export const getPlaylistTracks = async (
   accessToken: string,
   signal?: AbortSignal,
 ): Promise<SpotifyTrack[]> => {
-  const url = `${SPOTIFY_API_BASE_URL}/playlists/${playlist_id}/tracks`;
+  const url = `${SPOTIFY_API_BASE_URL}/playlists/${playlist_id}/items`;
   const data: SpotifyTrackResponse = await spotifyFetch(
     url,
     accessToken,
     signal,
   );
-  return data.items.map(item => item.track);
+  return data.items.map(i => i.item);
 };

src/types/SpotifyPlaylist.ts

@@ -7,7 +7,7 @@ export interface SpotifyPlaylistResponse {
 
 export interface SpotifyTrackResponse {
   items: {
-    track: SpotifyTrack;
+    item: SpotifyTrack;
   }[];
   total: number;
 }