Add missing type annotation

Author: markshannon

Tools/cases_generator/tier2_generator.py

@@ -139,7 +139,7 @@ def tier2_to_tier2(
         self.out.emit(")")
         return False
 
-def cache_items(emitter: Emitter, stack: Stack, cached_items: int, zero_regs: bool):
+def cache_items(emitter: Emitter, stack: Stack, cached_items: int, zero_regs: bool) -> None:
     emitter.out.start_line()
     i = cached_items
     while i > 0: