Export with official nn.SiLU() (#7256)

* Update

* Update time_limit

utils/general.py

@@ -738,7 +738,7 @@ def non_max_suppression(prediction,
     # min_wh = 2  # (pixels) minimum box width and height
     max_wh = 7680  # (pixels) maximum box width and height
     max_nms = 30000  # maximum number of boxes into torchvision.ops.nms()
-    time_limit = 0.030 * bs  # seconds to quit after
+    time_limit = 0.1 + 0.03 * bs  # seconds to quit after
     redundant = True  # require redundant detections
     multi_label &= nc > 1  # multiple labels per box (adds 0.5ms/img)
     merge = False  # use merge-NMS