Update the babel config

As suggested by the Discord

Author: Windvis

index.js

@@ -6,7 +6,11 @@ module.exports = {
   options: {
     babel: {
       // This is needed for dynamic imports to work: https://github.com/ef4/ember-auto-import#installing-ember-auto-import-in-an-addon
-      plugins: [require.resolve('ember-auto-import/babel-plugin')],
+      plugins: [
+        require.resolve('ember-auto-import/babel-plugin'),
+        // Copied from the v2 addon blueprint: https://github.com/embroider-build/addon-blueprint/blob/eef35575e7130ffe3b588ecd83c637f35fa56220/files/__addonLocation__/babel.config.json#L3
+        ["@babel/plugin-transform-typescript", { "allExtensions": true, "onlyRemoveTypeImports": true, "allowDeclareFields": true }]
+      ],
     },
     'ember-cli-babel': { enableTypeScriptTransform: true },
   },