Fix userinfo request method

[JUVOJustin]

All Submissions:

• [x] Have you followed the plugin Contributing guideline?
• [x] Does your code follow the WordPress' coding standards?
• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Change the userinfo request method from POST to GET. This is causing issues with some identity providers like cloudflare since the recommended method is GET.

How to test the changes in this Pull Request:

Just test idp´s as usual

Other information:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [x] Have you written new tests for your changes, as applicable?
• [x] Have you successfully run tests with your changes locally?

Changelog entry

Changed userinfo endpoint request to GET as this is the recommended method by The OpenID Foundation. Implicitly solves authentication issues with cloudflare zero trust.

[JUVOJustin]

Is there anything I can do to unblock this? It is such a minor patch which would solve OpenID auth especially for users that use cloudflare. Would love to see this in core.

If there is anything i can do to unblock pls let me know.

[timnolte]

At this point in the coming weeks I will be submitting my final patch for this plugin. At which point I'll be looking for new maintainers. I no longer have the energy for WordPress and the toxicity of Matt Mullenweg permeating the WordPress community. If there are no reputable maintainers that step up to take over this plugin then it will more than likely die off.