ci: bump actions/checkout from 5 to 6 (#613)

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
...

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

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: 'Checkout for CI 🛎️'
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: 'Set up JDK 21 📦'
         uses: actions/setup-java@v5
         with:

.github/workflows/pr_tests.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: 'Checkout for CI 🛎'
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: 'Set up JDK 21 📦'
         uses: actions/setup-java@v5
         with:

.github/workflows/release.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: 'Checkout for CI 🛎️'
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: 'Set up JDK 21 📦'
         uses: actions/setup-java@v5
         with:

.github/workflows/update_docs.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: 'Checkout for CI 🛎️'
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: 'Push Docs to Github Wiki 📄️'
         uses: Andrew-Chen-Wang/github-wiki-action@v5
         with: