tests: cache sample files

Author: henryborchers

.github/workflows/tox_matrix.yml

@@ -49,7 +49,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: "${{ github.workspace }}"
-          key: sample-images-${{ hashFiles('sample_images.tar.gz') }}
+          key: sample-images
       - name: download sample files
         if: steps.cache_samples.outputs.cache-hit != 'true'
         run: curl -L https://nexus.library.illinois.edu/repository/sample-data/images/sample_images.tar.gz -o "${{ github.workspace }}/sample_images.tar.gz"