docs: move the workflow example to actions/checkout@v7 (#12)

One line in `docs/guides/integrations.md`: `actions/checkout@v5` →
`@v7`.

v5 is two majors behind. This pin is copied verbatim by anyone following
the
guide, so it seeds every new workflow with a stale action. It was the
only
`checkout@` pin left in `docs/`.

The matching pins in `commit-check-action` (README,
`docs/fork-pr-comments.md`,
`examples/`) move in commit-check/commit-check-action#254.

---
_Generated by [Claude
Code](https://claude.ai/code/session_01U9zFxq8V4qxG4aMzJhGBFn)_

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Chores**
* Updated the GitHub Actions checkout configuration to use the latest
supported version.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Co-authored-by: Claude <noreply@anthropic.com>

Author: shenxianpeng

docs/guides/integrations.md

@@ -118,7 +118,7 @@ jobs:
     permissions:
       contents: read
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v7
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0        # (1)!