Bump react-router from 6.26.1 to 7.1.5 in /welcome

Bumps [react-router](https://github.com/remix-run/react-router/tree/HEAD/packages/react-router) from 6.26.1 to 7.1.5.
- [Release notes](https://github.com/remix-run/react-router/releases)
- [Changelog](https://github.com/remix-run/react-router/blob/main/packages/react-router/CHANGELOG.md)
- [Commits](https://github.com/remix-run/react-router/commits/react-router@7.1.5/packages/react-router)

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

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

Author: dependabot[bot]