tests: cache sample files

Author: henryborchers

.github/workflows/tox_matrix.yml

@@ -52,7 +52,7 @@ jobs:
           key: sample-images-${{ hashFiles('sample_images.tar.gz') }}
       - name: download sample files
         if: steps.cache_samples.outputs.cache-hit != 'true'
-        run: curl -L https://nexus.library.illinois.edu/repository/sample-data/images/sample_images.tar.gz -o "{{ github.workspace }}/sample_images.tar.gz"
+        run: curl -L https://nexus.library.illinois.edu/repository/sample-data/images/sample_images.tar.gz -o "${{ github.workspace }}/sample_images.tar.gz"
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}