Update unist-util-is

Author: wooorm

package.json

@@ -26,7 +26,7 @@
   ],
   "dependencies": {
     "flatmap": "0.0.3",
-    "unist-util-is": "^1.0.0"
+    "unist-util-is": "^2.0.0"
   },
   "devDependencies": {
     "tape": "^4.4.0",