Update tasks.py to allow custom RTEDTRDecoder arguments (#3872)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

ultralytics/nn/tasks.py

@@ -699,10 +699,12 @@ def parse_model(d, ch, verbose=True):  # model_dict, input_channels(3)
             args = [ch[f]]
         elif m is Concat:
             c2 = sum(ch[x] for x in f)
-        elif m in (Detect, Segment, Pose, RTDETRDecoder):
+        elif m in (Detect, Segment, Pose):
             args.append([ch[x] for x in f])
             if m is Segment:
                 args[2] = make_divisible(min(args[2], max_channels) * width, 8)
+        elif m is RTDETRDecoder:  # special case, channels arg must be passed in index 1
+            args.insert(1, [ch[x] for x in f])
         else:
             c2 = ch[f]