Update author properties to include .node

Update accessing author properties to include .node as part of the
upgrade of WPGraphQL to 0.12.1

See #17

Author: salcode

components/avatar.js

@@ -2,14 +2,14 @@ import PropTypes from 'prop-types'
 
 export default function Avatar({author}) {
   const name =
-    author.firstName && author.lastName
-      ? `${author.firstName} ${author.lastName}`
-      : author.name
+    author.node.firstName && author.node.lastName
+      ? `${author.node.firstName} ${author.node.lastName}`
+      : author.node.name
 
   return (
     <div className="flex items-center">
       <img
-        src={author.avatar.url}
+        src={author.node.avatar.url}
         className="w-12 h-12 rounded-full mr-4"
         alt={name}
       />