chore(deps): Upgrade `superagent` to v9.X

[abshierjoel]

Changes

Superagent has a patch for a publicly announced vulnerability now available in version 9.X. This PR updates the superagent dependency to the latest version.

warning auth0-js > [email protected]: Please upgrade to v9.0.0+ as we have fixed a public vulnerability with formidable dependency. Note that v9.0.0+ requires Node.js v14.18.0+. See https://github.com/ladjs/superagent/pull/1800 for insight. This project is supported and maintained by the team at Forward Email @ https://forwardemail.net

References

Please include relevant links supporting this change such as a:

• support ticket
• community post
• StackOverflow post
• support forum thread

Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. If this library has unit and/or integration testing, tests should be added for new functionality and existing tests should complete without errors.

• [ ] This change adds unit test coverage
• [ ] This change adds integration test coverage

Checklist

• [x] I have read the Auth0 general contribution guidelines
• [x] I have read the Auth0 Code of Conduct
• [x] All tests and linters described in the Develop section run without errors