Reconsider integration test strategy

[Frixxie]

From #36 :

However i am unsure how we should test the endpoints, i had some issues with the address already being allocated.
So for now i have used unique ports for all tests, however this is not maintainable, suggestions would be nice here

Alternatives are: https://docs.rs/axum-test/latest/axum_test/struct.TestServer.html and https://github.com/tokio-rs/axum/blob/main/examples/testing/src/main.rs

Or what i think would be nice: Some kind of fixture that sets up the web-server