feat: introduce AnthropicBetaProvider for beta API support

[koxudaxi]

TL;DR

Added support for Anthropic's beta API to enable strict structured output formatting.

What changed?

• Created a new beta package within the Anthropic provider implementation
• Implemented AnthropicBetaProvider class that uses Anthropic's beta API
• Added utility functions for encoding requests and decoding responses with the beta API
• Modified the main AnthropicProvider to conditionally use the beta provider when strict formatting is requested
• Updated error messages to include model ID in formatting mode errors
• Reorganized existing Anthropic utilities into a standard package

How to test?

1. Use the Anthropic provider with a model that supports strict structured output formatting:

   from mirascope import LLM
   from pydantic import BaseModel
   
   class MyOutput(BaseModel):
       name: str
       age: int
   
   llm = LLM(model="anthropic/claude-3-opus-20240229")
   response = llm.format(MyOutput, mode="strict").call("Generate a person's details")
   print(response.content)  # Will be a properly typed MyOutput instance

2. Verify that appropriate error messages are shown when using models that don't support strict formatting.

Why make this change?

Anthropic's beta API provides better support for strict structured output formatting, which allows for more reliable parsing of model outputs into Pydantic models. This change enables users to get properly typed outputs from Anthropic models that support this feature, improving type safety and reducing the need for error handling around parsing.

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[koxudaxi]

• refactor: reorg the AnthropicBetaProvider #1718 : 2 dependent PRs (#1702 , #1707 )
• feat: introduce AnthropicBetaProvider for beta API support #1713 👈 (View in Graphite)
• chore: include claude-sonnet-4-0 as a tracked anthropic model #1706
• chore: fixup mlx cassette tests #1705
• refactor: move ensure_additional_properties_false to base utils #1696
• feat: track strict structured output support for anthropic models #1695
• feat: bump anthropic to 0.75.0\ #1694
• feat: use model_features framework to track anthropic model ids #1693
• v2

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[willbakst]

The description code example is hilarious

[teamdandelion]

Merge activity

• Dec 18, 7:21 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Dec 18, 7:21 PM UTC: @teamdandelion merged this pull request with Graphite.