Small refactor for Go > 1.16

[ethrgeist]

I was not able to build the docker image due changes in golang, namely https://github.com/golang/go/issues/40276 and https://go.dev/doc/go-get-install-deprecation, also some things in the logging of prometheus changed, so i refactored a few things to get the dockerfile working again.

Feel free to merge. :)