Deploy Kubernetes container for authentication integration test

[stijnmoreels]

Not yet created integration test for Kuberetes authentication bc that would require me to create a Kubernetes service account (extra costs per month) and maybe not the worth the cost for that?
Of course if there's a way that this can be up shortcutted, and there's a way to test this external call by setting up a test server that validates the JWT token for us... we could maybe go that route.

Let's add a dedicated issue where we deploy a container to a Kind cluster and run against that.

Originally posted by @tomkerkhove in #165 (comment)

[stijnmoreels]

Prioritize .NET 8 support, moving to v2.1.