Value gppString in PingData is not updated when section is set to cmpApi.

[nejcsever]

When setting section value with string section value (cmpApi.setSectionString(sectionName, sectionValue)), gppString is unchanged in PingData object.

Here's the reproducible case where you can see that after setting the UspV1 section value, the gppString in the PingData of the event is still set to "DBAA":

import {CmpApi,CmpDisplayStatus,CmpStatus,SignalStatus,UspV1} from "@iabgpp/cmpapi";
import "@iabgpp/stub";

window.__gpp("addEventListener", (e) => console.log(e));

const cmpApi = new CmpApi(-1, 1);
cmpApi.setApplicableSections([6]);
cmpApi.setCmpStatus(CmpStatus.LOADED);
cmpApi.setSignalStatus(SignalStatus.NOT_READY);
cmpApi.setCmpDisplayStatus(CmpDisplayStatus.VISIBLE);
cmpApi.setSectionString(UspV1.NAME, "1YYY");
cmpApi.setCmpDisplayStatus(CmpDisplayStatus.HIDDEN);
cmpApi.setSignalStatus(SignalStatus.READY);

This happens because the "dirty" boolean flag inside gppModel is not set to true when this method is used (only when fields are updated). I think the case above should be supported. Changes to sections via setSectionString should be reflected in gppString in PingData.