Pin older Node version for 0.12 release branch 💄 (#747)

Author: ZeeJab

package.json

@@ -58,5 +58,9 @@
     "saucie": "^3.3.2",
     "testem": "^2.17.0"
   },
-  "main": "dist/commonjs/mobiledoc-kit/index.js"
+  "main": "dist/commonjs/mobiledoc-kit/index.js",
+  "volta": {
+    "node": "10.22.1",
+    "yarn": "1.22.5"
+  }
 }