Bump @rushstack/heft from 0.42.2 to 0.42.6

Bumps [@rushstack/heft](https://github.com/microsoft/rushstack/tree/HEAD/apps/heft) from 0.42.2 to 0.42.6.
- [Release notes](https://github.com/microsoft/rushstack/releases)
- [Changelog](https://github.com/microsoft/rushstack/blob/master/apps/heft/CHANGELOG.md)
- [Commits](https://github.com/microsoft/rushstack/commits/@rushstack/heft_v0.42.6/apps/heft)

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

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