[mpd] Update current song on player events (#8818)

This fixes #8817

Signed-off-by: Brian O'Connell <broconne@gmail.com>
(cherry picked from commit f5bf17875d)

bundles/org.openhab.binding.mpd/src/main/java/org/openhab/binding/mpd/internal/protocol/MPDConnection.java

@@ -193,6 +193,7 @@ public class MPDConnection implements MPDResponseListener {
                 switch (line) {
                     case "player":
                         updateStatus = true;
+                        updateCurrentSong = true;
                         break;
                     case "mixer":
                         updateStatus = true;