Bump mypy version

[davorrunje]

Why are these changes needed?

Related issue number

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• I've included any doc changes needed for https://docs.ag2.ai/. See https://docs.ag2.ai/docs/contributor-guide/documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Flag	Coverage Δ
3.10	58.58% <ø> (+2.71%)	⬆️
3.11	29.29% <ø> (?)
3.12	27.60% <ø> (?)
3.13	42.22% <ø> (+7.55%)	⬆️
3.9	40.36% <ø> (+6.63%)	⬆️
anthropic	16.35% <ø> (?)
bedrock	16.72% <ø> (?)
browser_use	29.38% <ø> (-0.01%)	⬇️
cerebras	16.43% <ø> (?)
cohere	16.48% <ø> (?)
crawl4ai	29.58% <ø> (-0.01%)	⬇️
docs	28.57% <ø> (-0.01%)	⬇️
falkordb	15.76% <ø> (?)
gemini	16.42% <ø> (?)
graph-rag-falkor-db	28.01% <ø> (-0.01%)	⬇️
groq	16.45% <ø> (?)
interop	29.44% <ø> (-0.01%)	⬇️
jupyter-executor	30.69% <ø> (-0.01%)	⬇️
lmm	19.29% <ø> (?)
long-context	15.59% <ø> (?)
macos-latest	58.95% <ø> (+2.65%)	⬆️
mistral	16.16% <ø> (?)
neo4j	15.78% <ø> (?)
ollama	16.85% <ø> (?)
retrievechat	29.56% <ø> (+0.03%)	⬆️
retrievechat-mongodb	29.55% <ø> (+1.26%)	⬆️
retrievechat-pgvector	29.55% <ø> (+1.26%)	⬆️
retrievechat-qdrant	29.50% <ø> (+1.28%)	⬆️
teachable	15.76% <ø> (?)
together	16.48% <ø> (?)
twilio	28.21% <ø> (-0.01%)	⬇️
ubuntu-latest	58.97% <ø> (+2.70%)	⬆️
websurfer	18.70% <ø> (?)
windows-latest	56.62% <ø> (+2.71%)	⬆️

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see 10 files with indirect coverage changes