Add missing dependency (#1936)

Add a missing dependency on `vfile`.

Reviewed-by: Titus Wormer <tituswormer@gmail.com>

Author: bensmithett

packages/rollup/package.json

@@ -40,7 +40,8 @@
   "dependencies": {
     "@mdx-js/mdx": "^2.0.0",
     "@rollup/pluginutils": "^4.0.0",
-    "source-map": "^0.7.0"
+    "source-map": "^0.7.0",
+    "vfile": "^5.0.0"
   },
   "peerDependencies": {
     "rollup": ">=2"