Equal 11 problem with input type of string

Describe the bug

ONNX Equal 11 does not support a type of string, but Equal version 11 in tf2onnx/onnx_opset/logical.py is implemented to support all types including string.

See https://github.com/onnx/onnx/blob/main/docs/Changelog.md#Equal-11 for supported types.

Note that the ONNX documentations shows that Equal-19 will support string. But, Equal version 11 in tf2onnx should still work with ONNX Equal 11.

Urgency

An update to tf2onnx/onnx_opset/logical.py is created to work around and a PR with the update will be submitted.

System information

• OS Platform and Distribution: macOS 13.2.1
• TensorFlow Version: 2.10.0
• Python version: 3.10.9
• ONNX version : 1.13.1
• ONNXRuntime: 1.13.1