Update unist-util-is

Author: wooorm

package.json

@@ -44,7 +44,7 @@
     "css-selector-parser": "^1.1.0",
     "not": "^0.1.0",
     "nth-check": "^1.0.1",
-    "unist-util-is": "^3.0.0",
+    "unist-util-is": "^4.0.0",
     "zwitch": "^1.0.3"
   },
   "devDependencies": {