fix: pin onnxmltools==1.13.0 (#262)

This PR resolves the issue where a upgraded version of the dependency was braking the code. Fixing it to the last working version so that it doesnt automatically upgrade in future.

Author: eliteprox

src/comfystream/scripts/constraints.txt

@@ -4,4 +4,5 @@ torchaudio==2.7.0
 xformers==0.0.30
 onnx==1.17.0
 onnxruntime==1.17.0
-onnxruntime-gpu==1.20.2
+onnxruntime-gpu==1.20.2
+onnxmltools==1.13.0