Update Dependabot config file

[dependabot-preview]

👋 Dependabot is moving natively into GitHub! This pull request updates your config file to 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.

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-commenter]

Codecov Report

Merging #203 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #203   +/-   ##
=========================================
  Coverage     88.08%   88.08%           
  Complexity       78       78           
=========================================
  Files             8        8           
  Lines           319      319           
  Branches         47       47           
=========================================
  Hits            281      281           
  Misses           30       30           
  Partials          8        8           

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