COCO8 and COCO8-seg Pytest and CI updates (#307)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: RangiLyu <lyuchqi@gmail.com>

ultralytics/nn/modules.py

@@ -82,7 +82,7 @@ class ConvTranspose(nn.Module):
 
 
 class DFL(nn.Module):
-    # DFL module
+    # Integral module of Distribution Focal Loss (DFL) proposed in Generalized Focal Loss https://ieeexplore.ieee.org/document/9792391
     def __init__(self, c1=16):
         super().__init__()
         self.conv = nn.Conv2d(c1, 1, 1, bias=False).requires_grad_(False)