tests: cache and verify hash value of sample images

Author: henryborchers

.github/workflows/tox_matrix.yml

@@ -63,7 +63,7 @@ jobs:
         id: cache
         with:
           path: "${{ matrix.conan_user_home }}/.conan2"
-          key: ${{ runner.os }}-${{ hashFiles('**/conanfile.py') }}
+          key: ${{ runner.os }}-${{ hashFiles('**/conanfile.py', 'conan.lock') }}
 
       - name: Build conan packages on Non-Windows Operating Systems
         if: ${{ !contains(matrix.os, 'windows') && steps.cache.outputs.cache-hit != 'true' }}