Fix incorrect type import

Author: wooorm

index.d.ts

@@ -1,5 +1,5 @@
+import type {Node as MdastNode} from 'unist'
 import type {
-  Node as MdastNode,
   Parent as MdastParent,
   Literal as MdastLiteral,
   BlockContent,

package.json

@@ -39,6 +39,7 @@
     "@types/estree-jsx": "^1.0.0",
     "@types/hast": "^2.0.0",
     "@types/mdast": "^3.0.0",
+    "@types/unist": "^2.0.0",
     "ccount": "^2.0.0",
     "mdast-util-from-markdown": "^1.1.0",
     "mdast-util-to-markdown": "^1.3.0",