fix: adapt to Ollama client 0.4.0

[anakin87]

Related Issues

• similar to fix: adapt to Ollama client 0.4.0 haystack-core-integrations#1209
• yesterday, a new version of the Ollama python client was released: they introduce pydantic and this breaks some of our assumptions to use python dictionaries
• See https://github.com/ollama/ollama-python/releases/tag/v0.4.0; add pydantic for validation and serialization ollama/ollama-python#276

Proposed Changes:

• update our code to make it work with ollama>=0.4.0
• depend on ollama-haystack>=2.0.0 (which pins ollama>=0.4.0 and works properly with this version)

How did you test it?

CI

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

[coveralls]

Pull Request Test Coverage Report for Build 11974659270

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.01%) to 81.912%

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Files with Coverage Reduction	New Missed Lines	%
components/generators/ollama/chat/chat_generator.py	5	93.18%

Totals
Change from base Build 11963918591:	0.01%
Covered Lines:	2305
Relevant Lines:	2814

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💛 - Coveralls

[anakin87]

All failing tests are unrelated: Anthropic overloaded; usual OpenAPITool failures.
I'm going to merge this PR.