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] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -47,7 +47,7 @@ jobs:
     name: "JDK ${{ matrix.java }}, ${{ matrix.compiler}}, params: ${{ matrix.parameters }}, ${{ matrix.os }}"
     steps:
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Set up JDK ${{ matrix.java }}
       uses: actions/setup-java@v5
@@ -76,7 +76,7 @@ jobs:
     name: 'Calcite regression test (JDK ${{ matrix.java }})'
     steps:
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
       with:
         fetch-depth: 50
 

.github/workflows/pages.yml

@@ -11,7 +11,7 @@ jobs:
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
       with:
         ref: gh-pages
 

.github/workflows/prepare-release.yml

@@ -33,7 +33,7 @@ jobs:
         private-key: ${{ secrets.CI_APP_PRIVATE_KEY }}
 
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
       with:
         ref: ${{ github.ref }}
         token: ${{steps.app-token.outputs.token}}
@@ -91,7 +91,7 @@ jobs:
         private-key: ${{ secrets.CI_APP_PRIVATE_KEY }}
 
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
       with:
         ref: ${{ github.ref }}
         token: ${{steps.app-token.outputs.token}}