Don't save lastResult in session.py.

Author: Ghislain Fourny

src/jsoniq/session.py

@@ -200,8 +200,7 @@ def bindDataFrameAsVariable(self, name: str, df):
 
     def jsoniq(self, str):
         sequence = self._jrumblesession.runQuery(str);
-        self.lastResult = SequenceOfItems(sequence, self);
-        return self.lastResult;
+        return SequenceOfItems(sequence, self);
 
     def __getattr__(self, item):
         return getattr(self._sparksession, item)