build(deps): bump actions/checkout from 4 to 7 (#2)

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](actions/checkout@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>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
       run:
         working-directory: backend
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
       - uses: astral-sh/setup-uv@v7
       - uses: actions/setup-python@v7
         with:
@@ -31,7 +31,7 @@ jobs:
       run:
         working-directory: frontend
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
       - uses: actions/setup-node@v4
         with:
           node-version: "24"