Revert "remove @babel line from babel.config"

This reverts commit af71304.

Author: beccaelenzil

babel.config.js

@@ -15,12 +15,12 @@ const presets = [
 ];
 
 const plugins = [
-  [
-    "module-resolver",
-    {
-      root: ["./src"],
-    },
-  ],
+  ["module-resolver", {
+    "root": ["./src"]
+  }],
+  ["@babel/plugin-proposal-class-properties", {
+    "loose": true
+  }],
 ];
 
 module.exports = { presets, plugins };