Do not wait forever when shutting down MercuryClient

Author: devgianlu

core/src/main/java/xyz/gianlu/librespot/mercury/MercuryClient.java

@@ -252,7 +252,7 @@ public void close() {
             } else {
                 synchronized (callbacks) {
                     try {
-                        callbacks.wait();
+                        callbacks.wait(100);
                     } catch (InterruptedException ignored) {
                     }
                 }