pmb.config.init: Don't convert sudo timer return value to str (MR 2434)

config.sudo_timer is a bool, and the returned value here is a bool. No
point in converting it to a str.

pmb/config/init.py

@@ -531,7 +531,7 @@ def ask_for_additional_options(config) -> None:
         "Enable background timer to prevent repeated sudo authorization?",
         default=context.sudo_timer,
     )
-    config.sudo_timer = str(answer)
+    config.sudo_timer = answer
 
     # Mirrors
     # prompt for mirror change