Remove ErrorTracker

Doesn't work with recent LiveView releases, and seems to be maintained
very slowly despite incoming PRs to fix the issues.

lib/music_library/application.ex

@@ -18,7 +18,6 @@ defmodule MusicLibrary.Application do
     children = [
       MusicLibrary.Vault,
       MusicLibrary.Repo,
-      MusicLibrary.ErrorRepo,
       MusicLibrary.BackgroundRepo,
       MusicLibraryWeb.Telemetry,
       {Oban, Application.fetch_env!(:music_library, Oban)},

lib/music_library/error_repo.ex

@@ -1,5 +0,0 @@
-defmodule MusicLibrary.ErrorRepo do
-  use Ecto.Repo,
-    otp_app: :music_library,
-    adapter: Ecto.Adapters.SQLite3
-end