CMakePM: Fix missing include

Change-Id: I7ed4045aa5b6b85fbf6a332161a3ad0e94bff348
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/cmakeprojectmanager/cmakebuildsystem.cpp

@@ -67,6 +67,7 @@
 #include <QJsonObject>
 #include <QLoggingCategory>
 #include <QPushButton>
+#include <QRegularExpression>
 
 using namespace ProjectExplorer;
 using namespace Utils;