Update dev-dependencies

Author: wooorm

package.json

@@ -37,7 +37,7 @@
     "browserify": "^16.0.0",
     "is-hidden": "^1.0.0",
     "not": "^0.1.0",
-    "nyc": "^14.0.0",
+    "nyc": "^15.0.0",
     "parse5": "^5.0.0",
     "prettier": "^1.0.0",
     "remark-cli": "^7.0.0",
@@ -46,7 +46,7 @@
     "tinyify": "^2.0.0",
     "to-vfile": "^6.0.0",
     "unist-util-visit": "^2.0.0",
-    "xo": "^0.25.0"
+    "xo": "^0.27.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier --write \"**/*.js\" && xo --fix",