Automate PlantUML JAR download

[asgrim]

Since the JAR filenames do not appear to be deterministic, manual update of the bundled JAR is currently needed.

You can download the latest JAR from https://github.com/plantuml/plantuml/releases.

We should figure out a way of automating the download of the JAR.

[ciaranmcnulty]

The public API has a sensible JSON object representing the latest release

curl https://api.github.com/repos/plantuml/plantuml/releases/latest | grep 'browser_download_url' | awk '{print $2}'

This and some regex may be enough? Or some jq cleverness

[asgrim]

Hmm, that gets us a little closer sure, but we'd need to find which of the assets is the right one we want (i.e. plantuml-1.2022.2.jar) which is also not deterministic :/

[Ocramius]

https://launchpad.net/ubuntu/+source/plantuml maybe? :|

[asgrim]

https://launchpad.net/ubuntu/+source/plantuml maybe? :|

this one looks way outdated :/