Metadata in logger for 1.15 Elixir

[hissssst]

Fixes #1070

[rrrene]

@hissssst Thank you for putting this together. As you can see in the checks, it unfortunately doesn't work in the greater scheme of things for Credo.

That being said, your PR inspired the commit referenced above, which should fix this for all supported versions of Elixir 👍

You can try this by setting the Credo dep to

{:credo, github: "rrrene/credo"}

Please report back if this works for your use-case 👍