remove type error suppressions in nerf_data_module

Summary: Remove `pyre-fixme` and `pyre-ignore` and fix the type errors.

Reviewed By: kandluis

Differential Revision: D29899546

fbshipit-source-id: dc8314f314bbc8acc002b8dbf21013cf3bafe65d

projects/nerf/nerf/eval_video_utils.py

@@ -9,6 +9,7 @@ from typing import Tuple
 
 import torch
 from pytorch3d.renderer import PerspectiveCameras, look_at_view_transform
+from torch.utils.data.dataset import Dataset
 
 
 def generate_eval_video_cameras(
@@ -18,7 +19,7 @@ def generate_eval_video_cameras(
     trajectory_scale: float = 0.2,
     scene_center: Tuple[float, float, float] = (0.0, 0.0, 0.0),
     up: Tuple[float, float, float] = (0.0, 0.0, 1.0),
-) -> dict:
+) -> Dataset[torch.Tensor]:
     """
     Generate a camera trajectory for visualizing a NeRF model.