Update @babel package to latest (generally 7.9.0)

[jamescdavis]

Update @babel/* dependencies to latest (generally 7.9.0).

This ensures that ember-cli-babel will use a version of Babel that includes babel/babel#11129 (included in 7.8.7) and TypeScript 3.8 support (included in 7.9.0) as well as other fixes and improvements included in Babel 7.9.0.

[jamescdavis]

Tests pass locally 🤔

[nicolo-ribaudo]

The bug on Travis is present in @babel/preset-env from version 7.8.0 to version 7.8.6. I don't know why it's included here 🤔

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EDIT: https://github.com/jamescdavis/ember-cli-babel/blob/32f6061514175f781f7f6399b89c560cc82ff668/yarn.lock#L770

Maybe try running npx yarn-deduplicate

[jamescdavis]

Thanks @nicolo-ribaudo, that worked!