Update dependency react-intl to v6.6.8

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
react-intl (source)	6.6.5 -> 6.6.8

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Release Notes

formatjs/formatjs (react-intl)

### [`v6.6.8`](https://togithub.com/formatjs/formatjs/releases/tag/react-intl%406.6.8) [Compare Source](https://togithub.com/formatjs/formatjs/compare/react-intl@6.6.7...react-intl@6.6.8) **Note:** Version bump only for package react-intl ### [`v6.6.7`](https://togithub.com/formatjs/formatjs/releases/tag/react-intl%406.6.7) [Compare Source](https://togithub.com/formatjs/formatjs/compare/react-intl@6.6.6...react-intl@6.6.7) **Note:** Version bump only for package react-intl ### [`v6.6.6`](https://togithub.com/formatjs/formatjs/compare/@formatjs/intl-displaynames@6.6.5...@formatjs/intl-displaynames@6.6.6) [Compare Source](https://togithub.com/formatjs/formatjs/compare/react-intl@6.6.5...react-intl@6.6.6)

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