Bump external/pipeline-Nextflow-config from f3448ac to af6a606

Bumps [external/pipeline-Nextflow-config](https://github.com/uclahs-cds/pipeline-Nextflow-config) from `f3448ac` to `af6a606`.
- [Release notes](https://github.com/uclahs-cds/pipeline-Nextflow-config/releases)
- [Commits](uclahs-cds/pipeline-Nextflow-config@f3448ac...af6a606)

---
updated-dependencies:
- dependency-name: external/pipeline-Nextflow-config
  dependency-type: direct:production
...

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