chore(deps): 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/cleanup.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Cleanup
         run: |

.github/workflows/codeql.yml

@@ -40,7 +40,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL

.github/workflows/gh_pkg.yaml

@@ -15,7 +15,7 @@ jobs:
       packages: 'write'
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       # .npmrc ファイルをセットアップして GitHub Packages に公開する
       - uses: actions/setup-node@v6

.github/workflows/npm_pkg.yaml

@@ -27,7 +27,7 @@ jobs:
           REL_NAME: ${{ github.event.release.name }}
           TAG_NAME: ${{ github.event.release.tag_name }}
 
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       # npm に公開するように .npmrc ファイルを設定する
       - uses: actions/setup-node@v6

.github/workflows/test.yaml

@@ -17,7 +17,7 @@ jobs:
         node-version: [18.x, 20.x, 22.x]
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Use Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v6