Remove use of wxGRIDTABLE_REQUEST_VIEW_GET_VALUES from the appearance panel

That even was removed by upstream wxWidgets in
81570ae070
which is included in all versions after 3.1.1, so our 3.2 versions
definitely aren't doing anything when we pass this event. The actual
identifier has also been guarded behind a 3.0 compatibility define in wx
as of 3.3.

pcbnew/widgets/appearance_controls.cpp

@@ -189,12 +189,6 @@ void NET_GRID_TABLE::SetValueAsCustom( int aRow, int aCol, const wxString& aType
 
     m_nets[aRow].color = VoidToColor( aValue );
     updateNetColor( m_nets[aRow] );
-
-    if( GetView() )
-    {
-        wxGridTableMessage msg( this, wxGRIDTABLE_REQUEST_VIEW_GET_VALUES );
-        GetView()->ProcessTableMessage( msg );
-    }
 }