langchain-openai==0.3.18

Changes since langchain-openai==0.3.17

openai: release 0.3.18 (#31320)
openai[patch]: relax Azure llm streaming callback test (#31319)
openai[patch]: support built-in code interpreter and remote MCP tools (#31304)
openai[patch]: run _tokenize in background thread in async embedding invocations (#31312)
openai[patch]: update tests for strict schemas (#31306)
openai[patch]: reduce tested constraints on strict schema adherence for Responses API (#31290)
openai[patch]: compat with Bedrock Converse (#31280)