Bump actions/setup-python from 5 to 6

Dependabot update for GitHub Actions setup-python.

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
           path: rdrobust-source
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.12"
 
@@ -57,7 +57,7 @@ jobs:
           path: rdrobust-source
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.12"