Keras namespace stubs are gone after upgrading to 2.15
@tbhaxor,
Hi,

Thanks for reporting the issue.

Since the migration, there were many changes made, the error you are getting is due to one such change here https://github.com/keras-team/tf-keras/commit/cff6ac903e2b8a0dde2a469d949f0f0ce3b5f282.

To get rid of the error, you need to install tf-keras-nightly as well as tf-nightly.

Note that, tf-keras-nightly is legacy Keras code, to use the Keras 3 with multi-backend support, use keras-nightly and import Keras directly.

Also the fix will be available once both Tensorflow and tf-keras do the next stable release, until then continue using as suggested. Thank you! Hi @tilakrayal Thanks for your response. Unfortunately it didn't work for me. 

Though it was not working with our process (we are using pypoetry). I have tried using virtualenv 

```console
cd $(mktemp -d)
virtualenv venv && source venv/bin/activate
pip install -U pip
pip install tf-keras-nightly tf-nightly

code .
```

On `tf.ker` it shows same output as uploaded above. Hi, 

Keras is migrated to Keras 3 with multi backend support.

Could you please install Keras separately using `pip install keras==3.0.0` and `import keras` directly and let us know the outcome with `keras.layers` etc Yes, we have already migrated to Keras 3 and it's working fine. Thanks for your response. Are you satisfied with the resolution of your issue?
<a href="https://docs.google.com/forms/d/e/1FAIpQLSfaP12TRhd9xSxjXZjcZFNXPGk4kc1-qMdv3gc6bEP90vY1ew/viewform?entry.85265664=Yes&entry.2137816233=https://github.com/tensorflow/tensorflow/issues/62491">Yes</a>
<a href="https://docs.google.com/forms/d/e/1FAIpQLSfaP12TRhd9xSxjXZjcZFNXPGk4kc1-qMdv3gc6bEP90vY1ew/viewform?entry.85265664=No&entry.2137816233=https://github.com/tensorflow/tensorflow/issues/62491">No</a>

### Issue type

Bug

### Have you reproduced the bug with TensorFlow Nightly?

No

### Source

source

### TensorFlow version

v2.15.0-rc1-8-g6887368d6d4

### Custom code

Yes

### OS platform and distribution

Arch Linux x64

### Mobile device

_No response_

### Python version

3.11

### Bazel version

_No response_

### GCC/compiler version

_No response_

### CUDA/cuDNN version

_No response_

### GPU model and memory

_No response_

### Current behavior?

I upgraded it from 2.14 to 2.15 and the keras intellisense stub in the vscode is missing.

![image](https://github.com/tensorflow/tensorflow/assets/28386721/8b9f63eb-3012-4758-b5de-a325ac9bfc83)

I restarted the LSP, still it doesn't show `keras` namespace. However, on checking in the REPL it shows the completion

![image](https://github.com/tensorflow/tensorflow/assets/28386721/a11bf08d-0c0c-466a-b647-d216be5a5b2e)



### Standalone code to reproduce the issue

```shell
import tensorflow as tf
```


### Relevant log output

_No response_