Bump react-intl from 6.8.1 to 6.8.4

Bumps [react-intl](https://github.com/formatjs/formatjs) from 6.8.1 to 6.8.4.
- [Release notes](https://github.com/formatjs/formatjs/releases)
- [Commits](https://github.com/formatjs/formatjs/compare/react-intl@6.8.1...react-intl@6.8.4)

---
updated-dependencies:
- dependency-name: react-intl
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>