Updates to allow the setting of the dateTime format string (#5763)

samples/client/petstore/cpp-qt5/PetStore/main.cpp

@@ -1,12 +1,14 @@
 #include <QCoreApplication>
 #include <QTest>
 
+#include "PFXHelpers.h"
 #include "PetApiTests.h"
 #include "StoreApiTests.h"
 #include "UserApiTests.h"
 
 int main(int argc, char *argv[]) {
     QCoreApplication a(argc, argv);
+    ::test_namespace::setDateTimeFormat("yyyy-MM-ddTHH:mm:ss.zzzZ");
     PetApiTests petApiTests;
     StoreApiTests storeApiTests;
     UserApiTests userApiTests;