Fix DDIM on Windows not using int64 for timesteps (#819)

src/diffusers/schedulers/scheduling_ddim.py

@@ -149,7 +149,7 @@ class DDIMScheduler(SchedulerMixin, ConfigMixin):
 
         # setable values
         self.num_inference_steps = None
-        self.timesteps = torch.from_numpy(np.arange(0, num_train_timesteps)[::-1].copy())
+        self.timesteps = torch.from_numpy(np.arange(0, num_train_timesteps)[::-1].copy().astype(np.int64))
 
     def scale_model_input(self, sample: torch.FloatTensor, timestep: Optional[int] = None) -> torch.FloatTensor:
         """
@@ -192,7 +192,7 @@ class DDIMScheduler(SchedulerMixin, ConfigMixin):
         step_ratio = self.config.num_train_timesteps // self.num_inference_steps
         # creates integer timesteps by multiplying by ratio
         # casting to int to avoid issues when num_inference_step is power of 3
-        timesteps = (np.arange(0, num_inference_steps) * step_ratio).round()[::-1].copy()
+        timesteps = (np.arange(0, num_inference_steps) * step_ratio).round()[::-1].copy().astype(np.int64)
         self.timesteps = torch.from_numpy(timesteps).to(device)
         self.timesteps += offset