Enable Nesting credo check

With two accepted exceptions

.credo.exs

@@ -3,9 +3,11 @@
     %{
       name: "default",
       checks: %{
+        extra: [
+          {Credo.Check.Refactor.Nesting, max_nesting: 3}
+        ],
         disabled: [
           {Credo.Check.Refactor.CyclomaticComplexity, []},
-          {Credo.Check.Refactor.Nesting, []},
           {Credo.Check.Readability.ModuleDoc, []}
         ]
       }

lib/mix/tasks/scrobble/audit.ex

@@ -307,6 +307,7 @@ defmodule Mix.Tasks.Scrobble.Audit do
         Enum.each(artist_issues.sample_tracks, fn %{artist: artist, sample_tracks: tracks} ->
           Mix.Shell.IO.info("\n  Artist: #{artist}")
 
+          # credo:disable-for-next-line Credo.Check.Refactor.Nesting
           Enum.each(tracks, fn track ->
             Mix.Shell.IO.info("    - #{track.title} (from #{track.album})")
           end)
@@ -343,6 +344,7 @@ defmodule Mix.Tasks.Scrobble.Audit do
                                                  } ->
           Mix.Shell.IO.info("\n  Album: #{album} by #{artist}")
 
+          # credo:disable-for-next-line Credo.Check.Refactor.Nesting
           Enum.each(tracks, fn track ->
             Mix.Shell.IO.info("    - #{track.title}")
           end)