Update pom.xml

[gurps-singh]

Updating json due to CVE-2023-5072

What problem does the pull request solve?

Upgrading JSON dependency to stable version due to dependency discovered in CVE-2023-5072

Checklist

• [x] I’ve used the pull request template
• [ ] I’ve written unit tests for these changes
• [ ] I’ve update the documentation (in DOCUMENTATION.md)
• [x ] I’ve bumped the version number
  • [x ] in src/main/resources/application.properties
  • [x ] in pom.xml

[samuelhwilliams]

Copied across to https://github.com/alphagov/notifications-java-client/pull/231 for our CI to run

Thanks for the contribution 🙏