Use braced initializer list in returns

Replaces explicit calls to the constructor in a return with a braced
initializer list.

lib/Pty.cpp

@@ -56,7 +56,7 @@ void Pty::setWindowSize(int lines, int cols)
 }
 QSize Pty::windowSize() const
 {
-    return QSize(_windowColumns,_windowLines);
+    return {_windowColumns,_windowLines};
 }
 
 void Pty::setFlowControlEnabled(bool enable)