fix(langchain): anthropic usage parsing

[hassiebp]

Greptile Summary

Disclaimer: Experimental PR review

This PR fixes the parsing of Anthropic usage data in the Langchain callback handler by filtering out non-numeric values from usage statistics.

• Modified _parse_usage_model in langfuse/callback/langchain.py to filter out string and None values from usage model dictionaries
• Ensures only valid numeric token counts are included in usage statistics for Anthropic models
• Prevents potential downstream processing issues from invalid usage data types

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Important

Fixes parsing of Anthropic usage data in Langchain by filtering out non-numeric values in langfuse/callback/langchain.py.

• Behavior:
  • Fix _parse_usage_model in langfuse/callback/langchain.py to filter out non-numeric values from usage model dictionaries.
  • Ensure only numeric token counts are included in Anthropic usage statistics.
  • Prevent downstream issues from invalid data types.
• Misc:
  • Minor formatting change in langfuse/extract_model.py.

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