fix(samples): correct return type annotation for _validate_shopping_agent#148

meetrick wants to merge 2 commits intogoogle-agentic-commerce:maingoogle-agentic-commerce/AP2:mainfrom

meetrick:meetrick/fix-validate-shopping-agent-return-typemeetrick/AP2:meetrick/fix-validate-shopping-agent-return-typeCopy head branch name to clipboard