Remove unnecessary ellipsis expressions (#9976)

Ignore flake8 F821 warnings in stub files

stdlib/random.pyi

@@ -100,9 +100,7 @@ class SystemRandom(Random):
     def getstate(self, *args: Any, **kwds: Any) -> NoReturn: ...
     def setstate(self, *args: Any, **kwds: Any) -> NoReturn: ...
 
-# ----- random function stubs -----
-
-_inst: Random = ...
+_inst: Random
 seed = _inst.seed
 random = _inst.random
 uniform = _inst.uniform