Avoid Qt's fractional scaling

Telegram/SourceFiles/core/launcher.cpp

@@ -287,6 +287,8 @@ void Launcher::init() {
 
 	QApplication::setApplicationName(qsl("TelegramDesktop"));
 	QApplication::setAttribute(Qt::AA_DisableHighDpiScaling, true);
+	QApplication::setHighDpiScaleFactorRoundingPolicy(
+		Qt::HighDpiScaleFactorRoundingPolicy::Floor);
 
 #if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
 	// fallback session management is useless for tdesktop since it doesn't have