Bump onnx in /mobile/examples/object_detection/ios/ORTObjectDetection

Bumps [onnx](https://github.com/onnx/onnx) from 1.10.0 to 1.13.0.
- [Release notes](https://github.com/onnx/onnx/releases)
- [Changelog](https://github.com/onnx/onnx/blob/main/docs/Changelog.md)
- [Commits](onnx/onnx@v1.10.0...v1.13.0)

---
updated-dependencies:
- dependency-name: onnx
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

mobile/examples/object_detection/ios/ORTObjectDetection/prepare_model.requirements.txt

@@ -1,4 +1,4 @@
-onnx==1.10.0
+onnx==1.13.0
 onnxruntime==1.13.1
 protobuf==3.19.6
 tensorflow==2.9.3