Bump dill from 0.3.8 to 0.3.9 in /docker/mlclustering

Bumps [dill](https://github.com/uqfoundation/dill) from 0.3.8 to 0.3.9.
- [Release notes](https://github.com/uqfoundation/dill/releases)
- [Commits](uqfoundation/dill@0.3.8...0.3.9)

---
updated-dependencies:
- dependency-name: dill
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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