Add type annotation for filter_items in OutputDataFrame

Introduces a type annotation for the filter_items variable in the OutputDataFrame class to improve code clarity and type checking.

Author: karangattu

shiny/playwright/controller/_output.py

@@ -1241,6 +1241,7 @@ def set_filter(
         if filter is None:
             return
 
+        filter_items: Sequence[ColumnFilter | dict[str, Any]]
         if isinstance(filter, dict):
             filter_items = [filter]
         elif isinstance(filter, (list, tuple)):