Remove babel-core dependency

[xjlim]

Fix #43

[kentcdodds]

Looks perfect! Thank you so much 👍

[codecov]

Codecov Report

Merging #44 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #44   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           4      4           
  Lines         101    101           
  Branches       21     21           
=====================================
  Hits          101    101

Impacted Files	Coverage Δ
src/get-replacement.js	100% <ø> (ø)	⬆️
src/macro.js	100% <100%> (ø)	⬆️
src/index.js	100% <100%> (ø)	⬆️

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[kentcdodds]

Thanks so much for your help! I've added you as a collaborator on the project. Please make sure that you review the other/MAINTAINING.md and CONTRIBUTING.md files (specifically the bit about the commit messages and the git hooks) and familiarize yourself with the code of conduct (we're using the contributor covenant). You might also want to watch the repo to be notified when someone files an issue/PR. Please continue to make PRs as you feel the need (you can make your branches directly on the repo rather than your fork if you want). Thanks! And welcome to the team :)