build(deps-dev): bump @rollup/plugin-babel from 6.0.3 to 6.0.4

Bumps [@rollup/plugin-babel](https://github.com/rollup/plugins/tree/HEAD/packages/babel) from 6.0.3 to 6.0.4.
- [Changelog](https://github.com/rollup/plugins/blob/master/packages/babel/CHANGELOG.md)
- [Commits](https://github.com/rollup/plugins/commits/babel-v6.0.4/packages/babel)

---
updated-dependencies:
- dependency-name: "@rollup/plugin-babel"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]