Update json to 2.7.0 and fix JSON.dump

What does this MR do and why?

Update json to 2.7.0 and fix JSON.dump, replacing !2548 (closed)

Make it clear we're passing hash literal

json 2.7.0 introduced a keyword argument, therefore this becomes ambiguous that we need to clarify.

We need to use {} to wrap around hashes: https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/5674820934

See https://my.diffend.io/gems/json/2.6.3/2.7.0

• Add a strict option to Generator #519 (closed)

https://github.com/flori/json/pull/519

Expected impact & dry-runs

These are strongly recommended to assist reviewers and reduce the time to merge your change.

See https://gitlab.com/gitlab-org/quality/triage-ops/-/tree/master/doc/scheduled#testing-policies-with-a-dry-run on how to perform dry-runs for new policies.

See https://gitlab.com/gitlab-org/quality/triage-ops/-/blob/master/doc/reactive/best_practices.md#use-the-sandbox-to-test-new-processors on how to make sure a new processor can be tested.

Action items

• If adding environment variables for reactive processors, update config/triage-web.yaml and .gitlab/ci/triage-web.yml
• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review