Re-enable *RCNN Onnx tests (#3319)

Author: datumbox

test/test_onnx.py

@@ -368,7 +368,6 @@ def get_test_images(self):
         test_images = [image2]
         return images, test_images
 
-    @unittest.skip  # Skip until pytorch/vision#3251 is fixed and pytorch/pytorch#50910 is merged.
     def test_faster_rcnn(self):
         images, test_images = self.get_test_images()
         dummy_image = [torch.ones(3, 100, 100) * 0.3]
@@ -420,7 +419,6 @@ def test_paste_mask_in_image(self):
 
         assert torch.all(out2.eq(out_trace2))
 
-    @unittest.skip  # Skip until pytorch/vision#3251 is fixed and pytorch/pytorch#50910 is merged.
     def test_mask_rcnn(self):
         images, test_images = self.get_test_images()
         dummy_image = [torch.ones(3, 100, 100) * 0.3]
@@ -471,7 +469,6 @@ def test_heatmaps_to_keypoints(self):
         assert torch.all(out2[0].eq(out_trace2[0]))
         assert torch.all(out2[1].eq(out_trace2[1]))
 
-    @unittest.skip  # Skip until pytorch/vision#3251 is fixed and pytorch/pytorch#50910 is merged.
     def test_keypoint_rcnn(self):
         images, test_images = self.get_test_images()
         dummy_images = [torch.ones(3, 100, 100) * 0.3]