Fix build with Qt5+C++20

Error was:
qvector.h:532:18: error: use of overloaded operator '!=' is ambiguous (with operand types 'int *' and 'QTypedArrayData<int>::iterator')
        while (i != d->begin())

src/private/multisplitter/Item.cpp

@@ -21,6 +21,7 @@
 #include <QTimer>
 #include <QGuiApplication>
 #include <QScreen>
+#include <algorithm>
 
 #ifdef Q_CC_MSVC
 #pragma warning(push)
@@ -2896,7 +2897,10 @@ QVector<int> ItemBoxContainer::calculateSqueezes(SizingInfo::List::ConstIterator
 
     const auto count = availabilities.count();
 
-    QVector<int> squeezes(count, 0);
+    QVector<int> squeezes;
+    squeezes.resize(count);
+    std::fill(squeezes.begin(), squeezes.end(), 0);
+
     int missing = needed;
 
     if (strategy == NeighbourSqueezeStrategy::AllNeighbours) {