Bump @rushstack/heft-web-rig from 0.4.29 to 0.4.31

Bumps [@rushstack/heft-web-rig](https://github.com/microsoft/rushstack/tree/HEAD/rigs/heft-web-rig) from 0.4.29 to 0.4.31.
- [Release notes](https://github.com/microsoft/rushstack/releases)
- [Changelog](https://github.com/microsoft/rushstack/blob/master/rigs/heft-web-rig/CHANGELOG.md)
- [Commits](https://github.com/microsoft/rushstack/commits/@rushstack/heft-web-rig_v0.4.31/rigs/heft-web-rig)

---
updated-dependencies:
- dependency-name: "@rushstack/heft-web-rig"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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