Update chalk requirement from ^1.1.3 to ^2.4.1

Updates the requirements on [chalk](https://github.com/chalk/chalk) to permit the latest version.
- [Release notes](https://github.com/chalk/chalk/releases)
- [Commits](https://github.com/chalk/chalk/commits/v2.4.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot-support

package.json

@@ -34,7 +34,7 @@
   "dependencies": {
     "babel-eslint": "^7.2.1",
     "bluebird": "^3.5.0",
-    "chalk": "^1.1.3",
+    "chalk": "^2.4.1",
     "hexo-fs": "^0.2.0",
     "hexo-util": "^0.6.0",
     "moment": "^2.18.0",