followPlaylist method
Follows a playlist identified by playlistId.
Optional isPublic sets whether the follow is public.
Implementation
Future<void> followPlaylist(String playlistId, {bool? isPublic}) async {
final uri = Uri.https(
_baseApiHost,
'/v1/playlists/$playlistId/followers',
);
final body = isPublic != null ? {'public': isPublic} : null;
await _putJson(uri, body);
}