Fix query for blog posts and featured image, add img package

src/components/Card.js

@@ -1,15 +1,17 @@
 import React from 'react'
 import Link from 'gatsby-link'
+import Img from 'gatsby-image'
 
 import ImgSprint from '../images/wow-we-did-design-sprint-remotely.png'
 
 const Card = ({ ...props }) => (
-  <article
-    key={props.postId}
-    className="my-4 lg:my-2 lg:mx-2 w-full rounded overflow-hidden shadow-md hover:shadow-lg"
-  >
+  <article className="my-4 lg:my-2 lg:mx-2 w-full rounded overflow-hidden shadow-md hover:shadow-lg">
     <Link to={props.url}>
-      <img className="w-full" src={ImgSprint} alt="Sprint Work" />
+      {props.image ? (
+        <Img resolutions={props.image} />
+      ) : (
+        <img className="w-full" src={ImgSprint} alt="Sprint Work" />
+      )}
     </Link>
     <div className="px-6 py-4">
       <div className="font-bold text-xl mb-2">