chore(cpn): update to Qt 5.15.2 and rework application packaging (#4270)

Co-authored-by: raphaelcoeffic <raphael.coeffic@frafos.com>
Co-authored-by: philmoz <phil.a.mitchell@gmail.com>

companion/src/helpers.cpp

@@ -264,7 +264,7 @@ void Helpers::populateFileComboBox(QComboBox * b, const QSet<QString> & set, con
 
   bool added = false;
   // Convert set into list and sort it alphabetically case insensitive
-  QStringList list = QStringList::fromSet(set);
+  QStringList list(set.begin(), set.end());
   std::sort(list.begin(), list.end(), caseInsensitiveLessThan);
   foreach (QString entry, list) {
     b->addItem(entry);