chore(deps): update postgres docker tag to v15.6 (#123)

Co-authored-by: Renovate Bot <renovate@whitesourcesoftware.com>

Author: github-renovate-self-hosted

.circleci/config.yml

@@ -20,7 +20,7 @@ executors:
         default: "3.10"
     docker:
       - image: cimg/python:<< parameters.python_version >>
-      - image: postgres:15.5
+      - image: postgres:15.6
         name: postgres
         environment:
           POSTGRES_HOST_AUTH_METHOD: trust