Properly include QStringList . Forward declaring it breaks with Qt6

9cc736c1 · Laurent Montel · 84591649 · 9cc736c1
Commit 9cc736c1 authored Dec 11, 2020 by Laurent Montel 😁
--- a/resources/mixedmaildir/autotests/testdatautil.h
+++ b/resources/mixedmaildir/autotests/testdatautil.h
@@ -9,7 +9,7 @@
 #define TESTDATAUTIL_H

 class QString;
-class QStringList;
+#include <QStringList>

 namespace TestDataUtil {
 enum FolderType {