Noisy warning in GPU build from Strumpack

```
70: -------------------------------------------------------
70: WARNING: SLATE is required for full GPU support.
70: SLATE is a GPU-capable replacement for ScaLAPACK, see
70: https://github.com/icl-utk-edu/slate
70: Configure with -DTPL_ENABLE_SLATE=ON
70: and set the SLATE_DIR environment variable.
70: -------------------------------------------------------
```

Start by locating the Strumpack GPU build path that emits the quoted SLATE warning and determine why it appears. Check the relevant GPU build or configuration output, then confirm the warning behavior expected for a normal build. Done means the noisy warning is addressed and the GPU build still completes as intended.

Written by the indexing model from the issue text.