Bump react-intl from 6.4.4 to 6.8.4

Bumps [react-intl](https://github.com/formatjs/formatjs) from 6.4.4 to 6.8.4.
- [Release notes](https://github.com/formatjs/formatjs/releases)
- [Commits](https://github.com/formatjs/formatjs/compare/[email protected]@6.8.4)

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

Signed-off-by: dependabot[bot] <[email protected]>