Uninstall: Update Token Revokation

[n7studios]

Summary

Updates the token revokation by using token_type_hint and setting the request Content-Type to application/x-www-form-urlencoded, based on the developer docs at https://developers.kit.com/api-reference/oauth-token-revocation

Testing

Existing tests pass.

Checklist

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)