Update dev-dependencies

Author: wooorm

package.json

@@ -24,13 +24,13 @@
     "hast-util-is-element": "^1.0.0"
   },
   "devDependencies": {
-    "browserify": "^14.0.0",
+    "browserify": "^16.0.0",
     "esmangle": "^1.0.1",
-    "nyc": "^11.0.0",
-    "remark-cli": "^4.0.0",
-    "remark-preset-wooorm": "^3.0.0",
+    "nyc": "^12.0.0",
+    "remark-cli": "^5.0.0",
+    "remark-preset-wooorm": "^4.0.0",
     "tape": "^4.4.0",
-    "xo": "^0.18.0"
+    "xo": "^0.21.0"
   },
   "scripts": {
     "build-md": "remark . --quiet --frail --output",

test.js

@@ -1,7 +1,7 @@
 'use strict';
 
 var test = require('tape');
-var heading = require('./');
+var heading = require('.');
 
 test('heading', function (t) {
   t.equal(