Why do you want to have that specific version of Vicidial for administration?
Vicidial is already installed with a matched version with goautodial. So why would you want an "unmatched" version instead? With the answer to that question, it may be possible for someone to assist with your true goal. Otherwise, if all you want is for it to say "2.12" instead of "2.9" in the version area, just change the text on that php page to "2.12" and you're done, LOL.
If you want a "full-on" upgrade of the Goautodial agent interface ...
Start with the Vicidial agent interface already installed in goautodial (with Vicidial 2.9). Then "diff" against the 2.12 version from the latest Vicidial agent interface. That will give you all the changes necessary for the agent interface to work from your old version to the new version. then you'll need to make all those changes in the GoAutodial version that matches the "2.9" and you'll end up with a version that matches 2.12 ... and then you can upgrade the DB so the full admin system works at the new version level. And post your results so that others can help you "keep it updated" over time as new versions come out.