Upgrade to ESLint 9 with flat config format#337

Copilot wants to merge 3 commits intocopilot/upgrade-husky-to-v9wellcomecollection/content-api:copilot/upgrade-husky-to-v9from

copilot/upgrade-eslint-to-9wellcomecollection/content-api:copilot/upgrade-eslint-to-9Copy head branch name to clipboard