Update dependency @babel/core to v7.6.4

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
@babel/core (source)	devDependencies	patch	7.6.3 -> 7.6.4

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Release Notes

babel/babel

### [`v7.6.4`](https://togithub.com/babel/babel/compare/v7.6.3...a422ea64ee2208a55dda33f990a422e14b917f5b) [Compare Source](https://togithub.com/babel/babel/compare/v7.6.3...a422ea64ee2208a55dda33f990a422e14b917f5b)

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