Update AI provider SDK versions and pin httpx dependency

[d-a-v-i--]

Update AI Provider SDK Versions and Fix Dependencies

Changes

• Update core AI provider SDK versions:
  • anthropic: 0.30.1 -> 0.40.0
  • openai: 1.35.8 -> 1.57.0
  • mistralai: 1.0.3 -> 1.2.5
  • vertexai: 1.63.0 -> 1.71.1
• Pin httpx to ~0.27.0 to resolve dependency conflicts between providers

Testing

• All tests passing (18/18)
• Coverage remains stable with core providers well-tested:
  • google_provider: 100%
  • groq_provider: 91%
  • mistral_provider: 91%
  • sambanova_provider: 92%

Motivation

Keep provider SDKs up to date with latest features and security patches while ensuring dependency compatibility across the suite.

Breaking Changes

None expected - version updates maintain backward compatibility