fix(deps)(deps): bump scikit-learn from 1.4.2 to 1.9.0 in /ml-service

Bumps [scikit-learn](https://github.com/scikit-learn/scikit-learn) from 1.4.2 to 1.9.0.
- [Release notes](https://github.com/scikit-learn/scikit-learn/releases)
- [Commits](scikit-learn/scikit-learn@1.4.2...1.9.0)

---
updated-dependencies:
- dependency-name: scikit-learn
  dependency-version: 1.9.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

ml-service/requirements.txt

@@ -5,4 +5,4 @@ redis==5.2.1
 
 # ML dependencies (optional – service degrades gracefully without them)
 numpy==1.26.4
-scikit-learn==1.4.2
+scikit-learn==1.9.0