Create Dependabot config file

[dependabot-preview]

👋 Dependabot is moving natively into GitHub! This pull request migrates your configuration from Dependabot.com to a config file, using the new syntax. When you merge this pull request, we'll swap out dependabot-preview (me) for a new dependabot app, and you'll be all set!

With this change, you'll now use the Dependabot page in GitHub, rather than the Dependabot dashboard, to monitor your version updates. Dependabot is now configured exclusively using config files.

The new version does not yet support private git dependencies. If you use these we recommend recommend leaving Dependabot Preview active.

If you've got any questions or feedback for us, please let us know by creating an issue in the dependabot/dependabot-core repository.

Learn more about the relaunch of Dependabot

Please note that regular @dependabot commands do not work on this pull request.

🤖💛

[codecov-io]

Codecov Report

Merging #49 (5ca7a95) into master (9e6ffa3) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #49   +/-   ##
=======================================
  Coverage   75.79%   75.79%           
=======================================
  Files           7        7           
  Lines         252      252           
=======================================
  Hits          191      191           
  Misses         37       37           
  Partials       24       24           

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