Changes since langchain==0.3.20
langchain[patch]: update text-splitters min bound (#30352)
langchain[patch]: lock with latest text-splitters (#30350)
langchain: release 0.3.21 (#30348)
Core: Adding Azure AI to Supported Chat Models (#30342)
fix(core): Ignore missing secrets on deserialization (#30252)
openai[patch]: support Responses API (#30231)
Fixed an issue with the OpenAI Assistant's 'retrieval' tool and adding support for the 'attachments' parameter (#30006)