Forward declare as much as possible

src/base/rss/rss_autodownloadrule.h

@@ -29,10 +29,10 @@
 
 #pragma once
 
-#include <QDateTime>
 #include <QSharedDataPointer>
 #include <QVariant>
 
+class QDateTime;
 class QJsonObject;
 class QRegularExpression;
 class TriStateBool;