chore: deprecate SklearnQueryClassifier

[anakin87]

Related Issues

• fixes Deprecate SklearnQueryClassifier #5323

Proposed Changes:

Classic deprecation procedure for SklearnQueryClassifier

How did you test it?

New deprecation warning test

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[julian-risch]

LGTM! 👍 Now that the SklearnQueryClassifier is deprecated, we should also remove that node from the tutorial (and thereby fix deepset-ai/haystack-tutorials#220). To make the transition simpler for users, we could also publish trained versions of the default models of SklearnQueryClassifier on the HF model hub. That would allow users to easily switch from SklearnQueryClassifier to TransformersQueryClassifier. I'd say let's just keep that in mind in case we later see requests. For now, usage of SklearnQueryClassifier seems too low to justify the extra effort.

[coveralls]

Pull Request Test Coverage Report for Build 5521286276

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 17 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.04%) to 45.293%

---

Files with Coverage Reduction	New Missed Lines	%
utils/context_matching.py	1	91.67%
nodes/query_classifier/sklearn.py	16	43.55%

Totals
Change from base Build 5519435104:	0.04%
Covered Lines:	10445
Relevant Lines:	23061

---

💛 - Coveralls