Update dev-dependencies

Author: wooorm

package.json

@@ -84,7 +84,7 @@
     "typescript": "^4.0.0",
     "unist-util-visit": "^4.0.0",
     "vfile": "^5.0.0",
-    "xo": "^0.49.0"
+    "xo": "^0.50.0"
   },
   "scripts": {
     "prepack": "npm run build && npm run format",