Bump actions/checkout from 6 to 7 in /.github/workflows

Bumps [actions/checkout](https://github.com/actions/checkout) from 6 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v6...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>

Author: dependabot[bot]

.github/workflows/backend_check.yml

@@ -31,7 +31,7 @@ jobs:
 
     steps:
       - name: Check out Git repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Install uv
         uses: astral-sh/setup-uv@v7
@@ -64,7 +64,7 @@ jobs:
 
     steps:
       - name: Check out Git repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Install uv
         uses: astral-sh/setup-uv@v7
@@ -111,7 +111,7 @@ jobs:
 
     steps:
       - name: Check out Git repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Install uv
         uses: astral-sh/setup-uv@v7
@@ -160,7 +160,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v4

.github/workflows/frontend_check.yml

@@ -39,7 +39,7 @@ jobs:
 
     steps:
       - name: Check out Git repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Set-up Node.js environment
         uses: actions/setup-node@v6