(4.x) Merge 3.4

testdata/dnn/download_models.py

@@ -884,6 +884,11 @@ def get_confirm_token(response):  # in case of large files
         url='https://github.com/AlexeyAB/darknet/releases/download/darknet_yolo_v4_pre/yolov4-tiny.weights',
         sha='d110379b7b86899226b591ad4affc7115f707157',
         filename='yolov4-tiny.weights'),
+    Model(
+        name='YOLOv4x-mish',  # https://github.com/opencv/opencv/issues/18975
+        url='https://github.com/AlexeyAB/darknet/releases/download/darknet_yolo_v4_pre/yolov4x-mish.weights',
+        sha='a6f2879af2241de2e9730d317a55db6afd0af00b',
+        filename='yolov4x-mish.weights'),
     Model(
         name='GSOC2016-GOTURN',  # https://github.com/opencv/opencv_contrib/issues/941
         downloader=GDrive('1j4UTqVE4EGaUFiK7a5I_CYX7twO9c5br'),

testdata/dnn/onnx/generate_onnx_models.py

@@ -367,6 +367,7 @@ def forward(self, x):
 model = Unsqueeze()
 model.eval()
 save_data_and_model("unsqueeze", input, model)
+save_data_and_model("unsqueeze_opset_13", input, model, version=13)
 
 input = Variable(torch.randn(1, 2, 4, 5))
 deconv_adjpad2d = nn.ConvTranspose2d(2, 3, (3, 2), stride=(1, 2), padding=(1, 2), output_padding=(0, 1))