Update dev-dependencies

Author: wooorm

package.json

@@ -41,7 +41,7 @@
     "parse-english": "^4.0.0",
     "parse-latin": "^4.0.0",
     "prettier": "^1.13.5",
-    "rehype": "^5.0.0",
+    "rehype": "^6.0.0",
     "remark-cli": "^5.0.0",
     "remark-preset-wooorm": "^4.0.0",
     "tape": "^4.0.0",