Bump azure-pipelines-task-lib from 4.5.0 to 4.9.1 in /cxAstScan

Bumps [azure-pipelines-task-lib](https://github.com/Microsoft/azure-pipelines-task-lib) from 4.5.0 to 4.9.1.
- [Commits](https://github.com/Microsoft/azure-pipelines-task-lib/commits)

---
updated-dependencies:
- dependency-name: azure-pipelines-task-lib
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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