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](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] <[email protected]>

Author: dependabot[bot]

.github/workflows/check-license.yml

@@ -13,7 +13,7 @@ jobs:
     name: Check License Header
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: apache/skywalking-eyes/header@main
         with:

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
       - name: Checkout Repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set up JDK 17
         uses: actions/setup-java@v5

.github/workflows/update-gradle-wrapper.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Update Gradle Wrapper
         uses: gradle-update/update-gradle-wrapper-action@v2