Incorrect import statement generated in python bindings

### What happened?

During the binding generation process the following line is created in `iree-build/runtime/bindings/python/iree/runtime/_binding.py`:
```
from .._runtime.libs import _runtime
```
This causes an error when trying to import iree-runtime python modules.

This can be trivially fixed by replacing the line above with
```
from .._runtime_libs import _runtime
```
Unfortunately, I'm not familiar with the binding generation methods used and cannot come up with an MR to fix it.

### Steps to reproduce your issue

1. Build IREE with python bindings
2. Try to import iree-runtime into a python script

### What component(s) does this issue relate to?

Python

### Version information

`14895845b Adding iree-benchmark-executable help text for CUDA.`

### Additional context

_No response_

Start with the generated file `iree-build/runtime/bindings/python/iree/runtime/_binding.py` and trace the binding-generation entry point that produces its import statement. Reproduce the Python import failure after building the bindings, then verify that the generated module imports successfully with the corrected `_runtime_libs` path.

Written by the indexing model from the issue text.