CI: checksumming the cache db to ensure it's always updated

Author: bsipocz

.circleci/config.yml

@@ -27,7 +27,7 @@ jobs:
             python -m tox -e py312-buildhtml
 
       - save_cache:
-          key: jupyter_ch
+          key: jupyter_ch-{{ checksum "_build/.jupyter_cache/global.db" }}
           paths:
             - _build/.jupyter_cache