Fixes this error:

In file included from /builddir/build/BUILD/MuseScore-4.2.1/src/project/internal/exporttype.cpp:22,
                 from /builddir/build/BUILD/MuseScore-4.2.1/redhat-linux-build/src/project/CMakeFiles/project.dir/Unity/unity_1_cxx.cxx:4:
/builddir/build/BUILD/MuseScore-4.2.1/src/project/internal/exporttype.h:31:36: error: expected template-name before ‘<’ token
   31 | class ExportTypeList : public QList<ExportType>
      |                                    ^
/builddir/build/BUILD/MuseScore-4.2.1/src/project/internal/exporttype.h:31:36: error: expected ‘{’ before ‘<’ token
/builddir/build/BUILD/MuseScore-4.2.1/src/project/internal/exporttype.h:31:36: error: expected unqualified-id before ‘<’ token

--- MuseScore-4.2.1/src/project/internal/exporttype.h.orig	2024-01-23 02:35:14.000000000 -0700
+++ MuseScore-4.2.1/src/project/internal/exporttype.h	2024-02-04 20:35:55.540782039 -0700
@@ -23,6 +23,7 @@
 #define MU_PROJECT_EXPORTTYPE_H
 
 #include <unordered_set>
+#include <QVariantList>
 
 #include "containers.h"