Add type annotations to server function

Imported Inputs, Outputs, and Session from shiny.session and updated the server function signature to include type annotations for improved type safety and clarity.

Author: karangattu

tests/playwright/shiny/bugs/2013-selectize-set-does-not-clear/app_selectize.py

@@ -1,4 +1,5 @@
 from shiny import App, render, ui
+from shiny.session import Inputs, Outputs, Session
 
 app_ui = ui.page_fluid(
     ui.input_selectize(
@@ -11,7 +12,7 @@
 )
 
 
-def server(input, output, session):
+def server(input: Inputs, output: Outputs, session: Session) -> None:
     @render.text
     def test_selectize_output():
         return f"Selected: {', '.join(input.test_selectize())}"