fix: remove mix files for emqx_lua_hook

apps/emqx_lua_hook/.formatter.exs

@@ -1,4 +0,0 @@
-# Used by "mix format"
-[
-  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
-]

apps/emqx_lua_hook/mix.exs

@@ -1,33 +0,0 @@
-defmodule EmqxLuaHook.MixProject do
-  use Mix.Project
-
-  def project do
-    [
-      app: :emqx_lua_hook,
-      version: "4.3.0",
-      build_path: "../../_build",
-      config_path: "../../config/config.exs",
-      deps_path: "../../deps",
-      lockfile: "../../mix.lock",
-      elixir: "~> 1.12",
-      start_permanent: Mix.env() == :prod,
-      deps: deps(),
-      description: "EMQ X Lua Hooks"
-    ]
-  end
-
-  def application do
-    [
-      mod: {:emqx_lua_hook_app, []},
-      extra_applications: [:logger]
-    ]
-  end
-
-  defp deps do
-    [
-      {:emqx, in_umbrella: true},
-      # {:luerl, github: "emqx/luerl", manager: :rebar3, tag: "v0.3.1"}
-      {:luerl, github: "rvirding/luerl", manager: :rebar3}
-    ]
-  end
-end