automate updates to other repos

[tritone]

This repo contains json and proto files which are copied to back conformance test cases/fixtures in other repos for specific client library languages. This process is not automated at all, which means it's easy for these files to get stale or out of sync.

This issue is to create a way to automatically open update issues or PRs when files are updated here.

Might be a good fixit week project.

[BenWhitehead]

Java has a semi-automated approach to updating from, in that someone has to run the script and open the PR. Everything else is handled automatically.

https://github.com/googleapis/java-conformance-tests/blob/main/bump-conformance-tests.sh