chore(deps): bump actions/checkout from 5 to 6 (#114)

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](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Georg Lauterbach <44545919+georglauterbach@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/linting.yml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           # super-linter needs the full git history to get the
           # list of files that changed across commits

.github/workflows/release.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           persist-credentials: false
 

.github/workflows/testing.yml

@@ -37,7 +37,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           persist-credentials: false
 
@@ -67,7 +67,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           persist-credentials: false