build(deps): bump actions/checkout from 6 to 7

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/build-test.yml

@@ -12,7 +12,7 @@ jobs:
     name: Debian Stable
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
 
     - name: Create Build Environment
       run: cd .github/ci/ && podman build -t tilix -f ./Dockerfile-debian-stable .
@@ -30,7 +30,7 @@ jobs:
     name: Debian Testing
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
 
     - name: Create Build Environment
       run: cd .github/ci/ && podman build -t tilix -f ./Dockerfile-debian-testing .
@@ -48,7 +48,7 @@ jobs:
     name: Ubuntu LTS
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
 
     - name: Create Build Environment
       run: cd .github/ci/ && podman build -t tilix -f ./Dockerfile-ubuntu-noble .
@@ -69,7 +69,7 @@ jobs:
         matrix:
           dc: [dmd-latest, ldc-latest]
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
 
     - name: Install System Dependencies
       run: |