QTest: remove static keyword from the new qWaitFor() chrono overload

This is a function template defined inside a namespace, `static` makes
no difference here.

Change-Id: I2eb52b4fb4432c269b2449ae37550bd0be0dbbce
Pick-to: 6.7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/kernel/qtestsupport_core.h

@@ -16,7 +16,7 @@ Q_CORE_EXPORT void qSleep(int ms);
 Q_CORE_EXPORT void qSleep(std::chrono::milliseconds msecs);
 
 template <typename Functor>
-[[nodiscard]] static bool
+[[nodiscard]] bool
 qWaitFor(Functor predicate, QDeadlineTimer deadline = QDeadlineTimer(std::chrono::seconds{5}))
 {
     // We should not spin the event loop in case the predicate is already true,