Fix test_dynamic_shapes.py and add it to CI.

## 🐛 Bug

xla/test/test_dynamic_shapes.py is currently failing and it is not included in the CI.

## To Reproduce



## Expected behavior

The test should pass and the test should be run as part of the CI.

## Environment

 - Reproducible on XLA backend [CPU/TPU]:
 - torch_xla version:


## Additional context