Add an artist filter for Rekt Network (web-scrobbler#4274)

- Extract original artist if it is Mixtape

src/connectors/rekt.network.ts

@@ -6,3 +6,14 @@ Connector.playerSelector = 'body';
 Connector.artistTrackSelector = '#nowplaying';
 
 Connector.playButtonSelector = '#playerPlay';
+
+const filter = MetadataFilter.createFilter({
+	artist: onlyArtist,
+});
+
+Connector.applyFilter(filter);
+
+function onlyArtist(artist: string) {
+	const chunks = artist.split('\n');
+	return chunks[chunks.length - 1];
+}