LangSmith SDK v0.8.15 dependency update

What's Changed

• chore(js): exclude generated _openapi_client from linters and type-checker by @KiewanVillatel in https://github.com/langchain-ai/langsmith-sdk/pull/3015
• chore: sync langsmith_api by @langtions-bot[bot] in https://github.com/langchain-ai/langsmith-sdk/pull/3006
• chore: protect JS openapi client in workflow by @KiewanVillatel in https://github.com/langchain-ai/langsmith-sdk/pull/3017
• fix(js): deliver sandbox output callbacks across stream reconnects by @langchain-infra in https://github.com/langchain-ai/langsmith-sdk/pull/3022
• fix(python): deliver sandbox output callbacks across stream reconnects by @langchain-infra in https://github.com/langchain-ai/langsmith-sdk/pull/3023
• chore: bump JS to 0.7.7 and Python to 0.8.15 by @langchain-infra in https://github.com/langchain-ai/langsmith-sdk/pull/3025

Full Changelog: https://github.com/langchain-ai/langsmith-sdk/compare/v0.8.14...v0.8.15