CI: 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
...

closes: #18803

Signed-off-by: dependabot[bot] <support@github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

.github/workflows/ci.yml

@@ -94,7 +94,7 @@ jobs:
 
     steps:
       - name: Checkout repository from github
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Check Filelist (for packaging)
         run: |
@@ -410,7 +410,7 @@ jobs:
 
     steps:
       - name: Checkout repository from github
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Install packages
         if: matrix.features == 'huge'
@@ -594,7 +594,7 @@ jobs:
           release: false
 
       - name: Checkout repository from github
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Create a list of download URLs
         shell: cmd

.github/workflows/codeql-analysis.yml

@@ -44,7 +44,7 @@ jobs:
 
     steps:
     - name: Checkout repository from github
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL

.github/workflows/coverity.yml

@@ -19,7 +19,7 @@ jobs:
     steps:
       - name: Checkout repository from github
         if: env.TOKEN
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Download Coverity
         if: env.TOKEN

.github/workflows/link-check.yml

@@ -8,7 +8,7 @@ jobs:
   lychee:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Run Lychee
         uses: lycheeverse/lychee-action@v2
         with: