build: (deps): bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [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/v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/integrate.yaml

@@ -8,7 +8,7 @@ jobs:
   code_tests:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - run: ./scripts/generate-locale-config.sh
       - run: git diff --exit-code
       - run: cat .github/workflows/versions.env >> $GITHUB_ENV
@@ -33,7 +33,7 @@ jobs:
   build_debug_apk:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - run: cat .github/workflows/versions.env >> $GITHUB_ENV
       - uses: actions/setup-java@v5
         with:
@@ -51,7 +51,7 @@ jobs:
   build_debug_web:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - run: cat .github/workflows/versions.env >> $GITHUB_ENV
       - uses: subosito/flutter-action@v2
         with:
@@ -70,7 +70,7 @@ jobs:
         arch: [ x64, arm64 ]
     runs-on: ${{ matrix.arch == 'arm64' && 'ubuntu-24.04-arm' || 'ubuntu-latest'}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - run: cat .github/workflows/versions.env >> $GITHUB_ENV
       - name: Install dependencies
         run: sudo apt-get update && sudo apt-get install git wget curl clang cmake ninja-build pkg-config libgtk-3-dev libblkid-dev liblzma-dev libjsoncpp-dev cmake-data libsecret-1-dev libsecret-1-0 librhash0 libssl-dev libwebkit2gtk-4.1-dev -y
@@ -85,7 +85,7 @@ jobs:
   build_debug_ios:
     runs-on: macos-15
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - run: cat .github/workflows/versions.env >> $GITHUB_ENV
       - uses: subosito/flutter-action@v2
         with: