Add GitHub workflow, cron-based to update driverless (AirPrint, IPP Everywhere) printer list

See issue #223, starting with this comment to the end.

@michaelrsweet said:

The current scripts merge the AirPrint and IPP Everywhere lists. Mopria does not provide a public list of printers (unfortunately), but the number of Mopria-ready printers that are not AirPrint or IPP Everywhere is probably close to (if not) 0.

I ran my scripts manually this time. I normally have them setup to run on one of my development systems once a month since the lists don't change that often. I don't think we could do this via GitHub CI directly - maybe we could create a PR but I'm not sure. The scripts can certainly be run from CI, it is just how to generate the PR with the changes? (I know I probably don't have the time to make that work right now, maybe later...)

... and to follow up on this, apparently there is a GitHub action for this. So it is possible we can do it fairly easily, but again I don't have time to write it up today...

From a clone of the repository:

cd driverless
./update-printer-list.sh

The updated "public/assets/json/driverless.json" file is then ready to be committed and/or turned into a PR.

The script uses curl and python, with the python sys and json modules/libraries (in case they are not in the default CI running image...)

For generating PRs also have a look at the workflows for update and versioning automation in the CUPS Snap repo.

@rudra-iitm @gativarshney @rkt0209 could somebody of you have a look?

Start with driverless/update-printer-list.sh and its generated public/assets/json/driverless.json file; review how the script uses curl and Python, including sys and json. Then inspect the update and versioning workflows in the CUPS Snap repo and the GitHub create-pull-request action. Done means a cron workflow runs the script and opens a pull request for updated printer data.