Introduce automation to keep ruby and java dependencies up to date

Managing dependencies on the Ruby and Java side requires a lot of effort (Gemfile.template, versions.yml, multiple build.gradle files, etc.).

I'd be nice to have an automated system that creates PRs to bump dependencies, and runs tests, potentially even merging when everything is green.

Start by reviewing Gemfile.template, versions.yml, and the multiple build.gradle files to map how Ruby and Java dependencies are currently maintained. Then inspect the repository's available automation and test entry points. Done means an agreed automated process creates dependency-update PRs, runs the relevant tests, and defines whether green updates may be merged automatically.

Written by the indexing model from the issue text.