Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

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

.github/workflows/linux.yaml

@@ -51,7 +51,7 @@ jobs:
           sudo apt install -y libc++abi-${{matrix.cxx}}-dev libc++-${{matrix.cxx}}-dev
 
       - name: Get pushed code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Configure
         run: cmake -S . -B _build ${{ env.CMAKE_OPTIONS }} -DCMAKE_INSTALL_PREFIX:STRING=${GITHUB_WORKSPACE}/_built
@@ -76,7 +76,7 @@ jobs:
         shell: alpine.sh {0}
     steps:
       - name: Get pushed code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - uses: jirutka/setup-alpine@v1
         with: