qt qrcode: fix DeprecationWarning (float->int conversion)

...\electrum\electrum\gui\qt\qrcodewidget.py:88: DeprecationWarning: an integer is required (got type float).  Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.
  qp.drawRect(left+c*boxsize, top+r*boxsize, boxsize - 1, boxsize - 1)

electrum/gui/qt/qrcodewidget.py

@@ -85,7 +85,8 @@ class QRCodeWidget(QWidget):
         for r in range(k):
             for c in range(k):
                 if matrix[r][c]:
-                    qp.drawRect(left+c*boxsize, top+r*boxsize, boxsize - 1, boxsize - 1)
+                    qp.drawRect(int(left+c*boxsize), int(top+r*boxsize),
+                                boxsize - 1, boxsize - 1)
         qp.end()