Add missing 'invalid' property.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@tp/tp-dropdown",
-  "version": "1.3.1",
+  "version": "1.3.2",
   "description": "",
   "main": "tp-dropdown.js",
   "scripts": {

tp-dropdown.js

@@ -283,6 +283,7 @@ class TpDropdown extends BaseElement {
       autoExtend: { type: Boolean, },
       focused: { type: Boolean, reflect: true, },
       readonly: { type: Boolean, reflect: true },
+      invalid: { type: Boolean, reflect: true },
       /*
       * Stores the first known value of the `value` property that is not falsy.
       * If `items` changes and no longer holds the originally selected item,