Update @types/node to the latest version 🚀

[greenkeeper[bot]]

Version 9.3.0 of @types/node was just published.

Dependency	@types/node
Current Version	8.5.8
Type	devDependency

The version 9.3.0 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.

It might be worth looking into these changes and trying to get this project onto the latest version of @types/node.

If you have a solid test suite and good coverage, a passing build is a strong indicator that you can take advantage of these changes directly by merging the proposed change into your project. If the build fails or you don’t have such unconditional trust in your tests, this branch is a great starting point for you to work on the update.

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Your Greenkeeper bot :palm_tree:

[codecov[bot]]

Codecov Report

Merging #6 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master       #6   +/-   ##
=======================================
  Coverage   45.54%   45.54%           
=======================================
  Files           1        1           
  Lines         191      191           
=======================================
  Hits           87       87           
  Misses        104      104

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