fix: expected.jsonのフォーマットを修正

- html-blocksの配列を一行に統一
- imageのexpected.jsonに末尾の改行を追加

Author: r74tech

tests/fixtures/html/fail/expected.json

@@ -55,7 +55,5 @@
       }
     }
   ],
-  "html-blocks": [
-    "body { display: none; }"
-  ]
+  "html-blocks": ["body { display: none; }"]
 }

tests/fixtures/image/basic/expected.json

@@ -514,4 +514,4 @@
       }
     }
   ]
-}
+}