Use QTransform.rotateRadians when appropriate

In a few places in the library, we are doing the conversion from radians
to degrees just so we can call QTransform.rotate(), but there is a
QTransform.rotateRadians() method which would be more suitable, thus
making it so we do not have to handle the conversions ourselves

pyqtgraph/graphicsItems/ROI.py

@@ -1524,7 +1524,7 @@ class Handle(UIGraphicsItem):
         devPos = dt.map(QtCore.QPointF(0,0))
         tr = QtGui.QTransform()
         tr.translate(devPos.x(), devPos.y())
-        tr.rotate(degrees(va))
+        tr.rotateRadians(va)
         
         return dti.map(tr.map(self.path))
         

pyqtgraph/graphicsItems/TargetItem.py

@@ -243,7 +243,7 @@ class TargetItem(UIGraphicsItem):
         tr = QtGui.QTransform()
         tr.translate(devPos.x(), devPos.y())
         va = atan2(v.y(), v.x())
-        tr.rotate(degrees(va))
+        tr.rotateRadians(va)
         tr.scale(self.scale, self.scale)
         return dti.map(tr.map(self._path))