pip prod(deps): update dask-cuda requirement from <25.6.1 to <25.8.1

Updates the requirements on [dask-cuda](https://github.com/rapidsai/dask-cuda) to permit the latest version.
- [Release notes](https://github.com/rapidsai/dask-cuda/releases)
- [Changelog](https://github.com/rapidsai/dask-cuda/blob/branch-25.10/CHANGELOG.md)
- [Commits](rapidsai/dask-cuda@v0.6.0.dev0...v25.08.00)

---
updated-dependencies:
- dependency-name: dask-cuda
  dependency-version: 25.8.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements-nvidia.txt

@@ -1,5 +1,5 @@
 cupy-cuda12x<13.5.2
-dask-cuda<25.6.1
+dask-cuda<25.8.1
 jupyterlab>=3,<4.4.2
 jupyterlab-nvdashboard<0.13.1
 dask_labextension<7.0.1