Bump @babel/polyfill from 7.10.4 to 7.12.1

Bumps [@babel/polyfill](https://github.com/babel/babel/tree/HEAD/packages/babel-polyfill) from 7.10.4 to 7.12.1.
- [Release notes](https://github.com/babel/babel/releases)
- [Commits](https://github.com/babel/babel/commits/v7.12.1/packages/babel-polyfill)

---
updated-dependencies:
- dependency-name: "@babel/polyfill"
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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