Bump react-intl from 5.8.2 to 6.4.0

Bumps [react-intl](https://github.com/formatjs/formatjs) from 5.8.2 to 6.4.0.
- [Release notes](https://github.com/formatjs/formatjs/releases)
- [Commits](https://github.com/formatjs/formatjs/compare/react-intl@5.8.2...react-intl@6.4.0)

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

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

package.json

@@ -150,7 +150,7 @@
         "react-collapse": "^4.0.3",
         "react-dom": "^16.13.1",
         "react-focus-trap": "^2.7.1",
-        "react-intl": "^5.8.2",
+        "react-intl": "^6.4.0",
         "react-modal": "^3.11.2",
         "react-motion": "^0.5.2",
         "react-pose": "^4.0.10",