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/ccpp.yml

@@ -12,7 +12,7 @@ jobs:
         os: [ubuntu-latest, macos-latest, windows-latest, windows-2019]
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Prepare dependencies
       run:   |
          if [ "$RUNNER_OS" == "Linux" ]; then

.github/workflows/doxygen-gh-pages.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout 🛎️
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Doxygen
         run: sudo apt-get install doxygen graphviz -y
       #- name: configure