ci(workflows): refresh deprecated python setup action

Align the CI Python setup step with the current action pin already used in the provenance workflow to remove the remaining deprecated Node 20 runtime warning.

Author: root

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
 
-      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
+      - uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
         with:
           python-version: "3.12"
           cache: pip