Replace `s.c.MapOps.mapValues` with `s.c.MapOps.view.mapValues`

@deprecated("Use .view.mapValues(f). A future version will include a strict version of this method (for now, .view.mapValues(f).toMap).", "2.13.0")
def mapValues[W](f: V => W): MapView[K, W] = new MapView.MapValues(this, f)