Bump external/pipeline-Nextflow-config in the pipeline-submodules group

Bumps the pipeline-submodules group with 1 update: [external/pipeline-Nextflow-config](https://github.com/uclahs-cds/pipeline-Nextflow-config).


Updates `external/pipeline-Nextflow-config` from `a4e99e0` to `23b7b4e`
- [Release notes](https://github.com/uclahs-cds/pipeline-Nextflow-config/releases)
- [Commits](uclahs-cds/pipeline-Nextflow-config@a4e99e0...23b7b4e)

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

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