Update async to the latest version 🚀

[greenkeeper[bot]]

The devDependency async was updated from 2.6.2 to 3.0.1.

This version is not covered by your current version range.

If you don’t accept this pull request, your project will work just like it did before. However, you might be missing out on a bunch of new features, fixes and/or performance improvements from the dependency update.

---

Find out more about this release.

FAQ and help

There is a collection of [frequently asked questions](https://greenkeeper.io/faq.html). If those don’t help, you can always [ask the humans behind Greenkeeper](https://github.com/greenkeeperio/greenkeeper/issues/new).

---

Your Greenkeeper bot :palm_tree:

[greenkeeper[bot]]

• The devDependency async was updated from 2.6.2 to 3.1.0.

Update to this version instead 🚀

[greenkeeper[bot]]

• The devDependency async was updated from 2.6.3 to 3.1.1.

Update to this version instead 🚀

[greenkeeper[bot]]

• The devDependency async was updated from 2.6.3 to 3.2.0.

Update to this version instead 🚀