remove hard coded value (pytorch#2793)

Co-authored-by: vfdev <vfdev.5@gmail.com>

torchvision/models/segmentation/deeplabv3.py

@@ -80,7 +80,7 @@ def __init__(self, in_channels, atrous_rates, out_channels=256):
         self.convs = nn.ModuleList(modules)
 
         self.project = nn.Sequential(
-            nn.Conv2d(5 * out_channels, out_channels, 1, bias=False),
+            nn.Conv2d(len(self.convs) * out_channels, out_channels, 1, bias=False),
             nn.BatchNorm2d(out_channels),
             nn.ReLU(),
             nn.Dropout(0.5))