Fix lower semver bound for dependency

Closes GH-61.

Author: wooorm

package.json

@@ -33,7 +33,7 @@
   "dependencies": {
     "extend": "^3.0.0",
     "hast-util-has-property": "^1.0.0",
-    "hast-util-is-element": "^1.0.0",
+    "hast-util-is-element": "^1.1.0",
     "hast-util-to-text": "^2.0.0",
     "mdast-util-phrasing": "^2.0.0",
     "mdast-util-to-string": "^1.0.0",