Bump actions/checkout from 2 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...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/check_external_links.yaml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         npm install -g markdown-link-check

.github/workflows/update_documentation.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: 2.7
@@ -26,7 +26,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Check file names
         run: |
           ./tools/check-file-names.sh
@@ -35,7 +35,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install dependencies
         run: |
           sudo apt-get install --yes shellcheck
@@ -47,7 +47,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install dependencies
         run: |
           pip install -r tools/requirements.txt
@@ -68,8 +68,8 @@ jobs:
     needs: [check_markdown_syntax, check_file_names, check_shell_scripts, check_python_scripts]
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
+      - uses: actions/checkout@v4
         with:
           repository: rucio/rucio
           ref: master
@@ -99,7 +99,7 @@ jobs:
     if: github.ref == 'refs/heads/main' || github.event_name == 'schedule'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/download-artifact@master
         with:
           name: documentation-artifacts