X-AUTH-* deprecated

[pkoevesdi]

The X-AUTH-* authorization, see https://www.kimai.org/documentation/2.13.0/user-api.html, is deprecated and does not work on our on-premise-installation of current Kimai, although it works on the current Kimai Demo.
Correct authorization scheme is Authorization: Bearer, see https://www.kimai.org/documentation/user-api.html.

I'll make a pull request.

[pkoevesdi]

Side note: I saw, X-AUTH-* probably still works (didn't try), when setting and using an API password instead of a token, see https://demo-stable.kimai.org/de/profile/susan_super/api-token. But anyway, also there it's marked as deprecated.