Upgrade setup-python action to version 6 (#16450)

## Summary

<!-- What's the purpose of the change? What does it do, and why? -->

This pull request updates the GitHub Actions workflow documentation to
use the latest version of the `actions/setup-python` action. This
ensures compatibility with recent improvements and bug fixes in the
action.

Workflow version updates:

* Updated the `uses: actions/setup-python` step from version `v5` to
`v6` in two separate workflow job examples in
`docs/guides/integration/github.md`.
[[1]](diffhunk://#diff-e864b910728c865e8e16ddb7892761fc2ef4838f2bf256eb1e20c35b24edd9fbL96-R96)
[[2]](diffhunk://#diff-e864b910728c865e8e16ddb7892761fc2ef4838f2bf256eb1e20c35b24edd9fbL119-R119)

docs/guides/integration/github.md

@@ -93,7 +93,7 @@ jobs:
       - uses: actions/checkout@v5
 
       - name: "Set up Python"
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version-file: ".python-version"
 
@@ -116,7 +116,7 @@ jobs:
       - uses: actions/checkout@v5
 
       - name: "Set up Python"
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version-file: "pyproject.toml"