Update actions/setup-python action to v6

Author: renovate[bot]

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
           path: "user_setup"
 
       - name: Set up Python 3.
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.x"
 
@@ -53,7 +53,7 @@ jobs:
           path: "user_setup"
 
       - name: Set up Python 3.
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.x"