[brief] Fixes a mypy error introduced by PyTorch 2.5.0.

[detailed]
- They changed the type-hints for the onnx.export function, so just tell
  mypy to ignore the "error" as the code is still correct.

src/helios/onnx.py

@@ -38,7 +38,7 @@ def export_to_onnx(
     with torch.no_grad():
         out = net(net_args)
 
-    torch.onnx.export(net, net_args, str(out_path), **kwargs)
+    torch.onnx.export(net, net_args, str(out_path), **kwargs)  # type: ignore[arg-type]
 
     onnx_model = onnx.load(out_path)
     onnx.checker.check_model(onnx_model)