volta: Pin Node.js and yarn versions

This will make it easier to use the same versions as we also use on Heroku.

see https://volta.sh

Author: Turbo87

package.json

@@ -143,5 +143,9 @@
   },
   "ember": {
     "edition": "octane"
+  },
+  "volta": {
+    "node": "16.13.2",
+    "yarn": "1.22.17"
   }
 }