Bump actions/checkout from 5.0.0 to 6.0.0 (#3061)

Bumps [actions/checkout](https://github.com/actions/checkout) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@08c6903...1af3b93)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/check-deprecated-exercises.yml

@@ -14,7 +14,7 @@ jobs:
     name: Check for deprecated exercises
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
         with:
           fetch-depth: 0
       - name: Test deprecated exercises using test-deprecated-exercises

.github/workflows/java.yml

@@ -15,7 +15,7 @@ jobs:
     name: Check if tests compile cleanly with starter sources
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
       - name: Set up JDK 1.17
         uses: actions/setup-java@dded0888837ed1f317902acf8a20df0ad188d165
         with:
@@ -29,7 +29,7 @@ jobs:
     name: Lint Java files using Checkstyle
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
       - name: Set up JDK 1.17
         uses: actions/setup-java@dded0888837ed1f317902acf8a20df0ad188d165
         with:
@@ -44,7 +44,7 @@ jobs:
     if: github.event_name == 'push' || github.event_name == 'workflow_dispatch'
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
       - name: Test all exercises using java-test-runner
         run: bin/test-with-test-runner
       - name: Print summary
@@ -71,7 +71,7 @@ jobs:
     if: github.event_name == 'pull_request'
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
         with:
           fetch-depth: 0
       - name: Test changed exercises using java-test-runner

.github/workflows/markdown.yml

@@ -17,6 +17,6 @@ jobs:
     name: Lint Markdown files
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
       - name: Lint markdown
         uses: DavidAnson/markdownlint-cli2-action@30a0e04f1870d58f8d717450cc6134995f993c63