Fix deprecation warnings on Elixir 1.19+: move 'preferred_cli_env' to 'cli/0', replace 'Mix.Config' with 'Config'

Author: acrogenesis

config/test.exs

@@ -1,4 +1,4 @@
-import Mix.Config
+import Config
 
 config :elixir_auth_google,
   client_id: "631770888008-6n0oruvsm16kbkqg6u76p5cv5kfkcekt.apps.googleusercontent.com",

mix.exs

@@ -15,8 +15,13 @@ defmodule ElixirAuthGoogle.MixProject do
       package: package(),
       aliases: aliases(),
       # coverage
-      test_coverage: [tool: ExCoveralls],
-      preferred_cli_env: [
+      test_coverage: [tool: ExCoveralls]
+    ]
+  end
+
+  def cli do
+    [
+      preferred_envs: [
         c: :test,
         coveralls: :test,
         "coveralls.json": :test,