File ppplay-fix-missing-include.patch of Package ppplay

Index: ppplay-0.1.3+git20190918/src/ppg/label.h
===================================================================
--- ppplay-0.1.3+git20190918.orig/src/ppg/label.h
+++ ppplay-0.1.3+git20190918/src/ppg/label.h
@@ -22,6 +22,7 @@
 #include "widget.h"
 
 #include <vector>
+#include <string>
 
 /**
  * @ingroup Ppg