Update to Phoenix 1.6.6

Update by applying https://gist.github.com/chrismccord/2ab350f154235ad4a4d0f4de6decba7b
JS hooks not working yet.

config/config.exs

@@ -29,3 +29,12 @@ config :phoenix, :json_library, Jason
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.
 import_config "#{Mix.env()}.exs"
+
+# Configure esbuild (the version is required)
+config :esbuild,
+  version: "0.12.18",
+  default: [
+    args: ~w(js/app.js --bundle --target=es2016 --outdir=../priv/static/assets),
+    cd: Path.expand("../assets", __DIR__),
+    env: %{"NODE_PATH" => Path.expand("../deps", __DIR__)}
+  ]