chore(cli): add mypy strict checking (#32386)

Co-authored-by: Mason Daugherty <mason@langchain.dev>

libs/cli/langchain_cli/namespaces/migrate/generate/utils.py

@@ -24,7 +24,7 @@ class ImportExtractor(ast.NodeVisitor):
 
     def __init__(self, *, from_package: Optional[str] = None) -> None:
         """Extract all imports from the given code, optionally filtering by package."""
-        self.imports: list = []
+        self.imports: list[tuple[str, str]] = []
         self.package = from_package
 
     @override