v1.6.4 Wrong predicted class names

### Search before asking - [x] I have searched the RF-DETR issues and found no similar bug report. ### Bug ```py from rfdetr import RFDETRSegSmall model = RFDETRSegSmall() detections = model.predict("https://media.roboflow.com/dog.jpg", threshold=0.5) print(detections.data["class_name"]) ``` It output: ['sheep' 'tie' 'motorcycle']. However, it supposed to output "dog". ### Environment RF-DETR 1.6.4 ### Minimal Reproducible Example ```py from rfdetr import RFDETRSegSmall model = RFDETRSegSmall() detections = model.predict("https://media.roboflow.com/dog.jpg", threshold=0.5) print(detections.data["class_name"]) ``` ### Additional _No response_ ### Are you willing to submit a PR? - [x] Yes, I'd like to help by submitting a PR!