chore(deps): bump actions/checkout from 4 to 7 (#155)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v4...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/flatter.yml

@@ -40,7 +40,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
         with:
           ref: ${{ inputs.tag_name || github.ref }}
 
@@ -103,7 +103,7 @@ jobs:
           pattern: ru.arabianq.pwsp-*
 
       - name: Checkout existing gh-pages
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
         with:
           ref: gh-pages
           path: gh-pages-branch