[CI] Bump actions/setup-python from 5 to 6 (#7298)

Bumps [actions/setup-python](https://github.com/actions/setup-python)from 5 to 6.

- vLLM version: v0.17.0
- vLLM main:
4034c3d32e

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/schedule_update_estimated_time.yaml

@@ -52,7 +52,7 @@ jobs:
           merge-multiple: false
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: '3.11'