Add explicit

src/engine/gstelementdeleter.h

@@ -32,7 +32,7 @@ class GstElementDeleter : public QObject {
   Q_OBJECT
 
  public:
-  GstElementDeleter(QObject *parent = nullptr);
+  explicit GstElementDeleter(QObject *parent = nullptr);
 
   // If you call this function with any gstreamer element, the element will get deleted in the main thread.
   // This is useful if you need to delete an element from its own callback.