add pytest-asyncio to tox.jinja

Author: shellmayr

scripts/populate_tox/tox.jinja

@@ -239,6 +239,7 @@ deps =
     httpx-latest: httpx
 
     # Langchain
+    langchain: pytest-asyncio
     langchain-v0.1: openai~=1.0.0
     langchain-v0.1: langchain~=0.1.11
     langchain-v0.1: tiktoken~=0.6.0