fix(nyz): fix default max step dtype bug (#163)

Author: sailxjx

ding/framework/task.py

@@ -118,7 +118,7 @@ def use_step_wrapper(self, fn: Callable) -> 'Task':
         self.step_wrappers.append(fn)
         return self
 
-    def run(self, max_step: int = 1e10) -> None:
+    def run(self, max_step: int = int(1e10)) -> None:
         """
         Overview:
             Execute the iterations, when reach the max_step or task.finish is true,