Update actions/checkout action to v7

| datasource  | package          | from | to     |
| ----------- | ---------------- | ---- | ------ |
| github-tags | actions/checkout | v6   | v7.0.0 |

Author: renovate[bot]

.github/workflows/release-on-milestone-closed-triggering-release-event.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v6"
+        uses: "actions/checkout@v7"
 
       - name: "Release"
         uses: "laminas/automatic-releases@v1"