chore(pixi): add bs4. [no ci]

Author: pabroux

pixi.lock

@@ -3,7 +3,7 @@ authors = [{name = "pabroux", email = "[email protected]"}]
 name = "tmp"
 requires-python = ">= 3.11"
 version = "0.1.0"
-dependencies = [ "langgraph>=0.4.8,<0.5", "langsmith>=0.3.45,<0.4", "typing-extensions>=4.14.0,<5", "langchain[openai]>=0.3.25,<0.4", "langchain-tavily>=0.2.1,<0.3", "ruff>=0.12.1,<0.13", "langchain-community>=0.3.25,<0.4", "pypdf>=5.7.0,<6", "pydantic>=2.11.7,<3", "pyupgrade>=3.20.0,<4"]
+dependencies = [ "langgraph>=0.4.8,<0.5", "langsmith>=0.3.45,<0.4", "typing-extensions>=4.14.0,<5", "langchain[openai]>=0.3.25,<0.4", "langchain-tavily>=0.2.1,<0.3", "ruff>=0.12.1,<0.13", "langchain-community>=0.3.25,<0.4", "pypdf>=5.7.0,<6", "pydantic>=2.11.7,<3", "pyupgrade>=3.20.0,<4", "bs4>=0.0.2,<0.0.3"]
 
 [build-system]
 build-backend = "hatchling.build"