Fix CoC updating workflow

[tekktrik]

Fixes #281

1. Uses jq to correctly turn the list of repositories into JSON for parsing in the child workflow.
2. Corrects the workflow to use exit to end the workflow early when skipping the source repository.
3. Performs checkouts for both the source and target repositories, using the Brutus token twice - once in the checkout so git operations use its permission, and as GH_TOKEN so the gh CLI creates the PR with its permissions.

Proof of Concept:

• Test repository w/ successful workflow run
• Target repository where PR was created (Workflow was slightly modified to only PR this specific repo)

Happy to add the same trick as in the Proof of Concept if we want to be extra safe.

[freakboy3742]

Thanks for those updates; the demo run definitely looks promising.

I'll add a safety catch on main before running it for the first time, then remove for a first "real" run.