Bump react-bootstrap from 1.6.4 to 2.10.9 in /example

Bumps [react-bootstrap](https://github.com/react-bootstrap/react-bootstrap) from 1.6.4 to 2.10.9.
- [Release notes](https://github.com/react-bootstrap/react-bootstrap/releases)
- [Changelog](https://github.com/react-bootstrap/react-bootstrap/blob/master/CHANGELOG.md)
- [Commits](react-bootstrap/react-bootstrap@v1.6.4...v2.10.9)

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

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

Author: dependabot[bot]