langchain-openai==0.3.15

Changes since langchain-openai==0.3.14

openai[patch]: release 0.3.15 (#31087)
packaging: remove Python upper bound for langchain and co libs (#31025)
langchain_openai: clean duplicate code for openai embedding. (#30872)
docs: document OpenAI flex processing (#31023)
openai[patch]: add explicit attribute for service tier (#31005)
openai[patch]: delete redundant tests (#31004)
openai: fix streaming reasoning without summaries (#30999)
core, standard-tests: support PDF and audio input in Chat Completions format (#30979)
core, openai: support standard multi-modal blocks in convert_to_openai_messages (#30968)
openai[patch]: remove xfails from image token counting tests (#30963)
Support of openai reasoning summary streaming (#30909)
partners/openai: OpenAIEmbeddings not respecting chunk_size argument (#30757)