Python XDataSeries - Don't use RideFileCommand when readOnly

It is unnecessary and too slow
Fixes #3445

src/Python/SIP/Bindings.cpp

@@ -879,7 +879,7 @@ PythonXDataSeries::PythonXDataSeries()
 
 bool PythonXDataSeries::set(int i, double value)
 {
-    if (rideFile) {
+    if (!readOnly && rideFile) {
         if (!setColIdx()){
             return false;
         }