Update dev version rule for nightly

[SamanehSaadat]

The keras-hub-nightly release workflow is broken with the following error message:

ERROR Backend subprocess exited when trying to invoke get_requires_for_build_sdist
* Creating isolated environment: venv+pip...
* Installing packages in isolated environment:
  - setuptools >= 40.8.0
* Getting build dependencies for sdist...
error in keras-nlp-nightly setup command: 'install_requires' must be a string or iterable of strings containing valid project/version requirement specifiers; Expected end or semicolon (after version specifier)
    keras-hub-nightly==0.20.0.dev0.dev2025030703[53](https://github.com/keras-team/keras-hub/actions/runs/13712977424/job/38353921561#step:7:54)

This PR updates the version naming rule to fix this.

[mattdangerw]

Thanks!