Update actions/checkout action to v6 (#65)

Co-authored-by: Renovate Bot <[email protected]>

Author: ata-no-one

.github/workflows/github-release.yaml

@@ -18,7 +18,7 @@ jobs:
       plugin_version: ${{ steps.get-version.outputs.plugin_version }}
       plugin_prerelease: ${{ steps.get-version.outputs.plugin_prerelease }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - id: get-version
         run: |
           if [[ $GITHUB_REF == refs/tags/v* ]]; then
@@ -54,7 +54,7 @@ jobs:
     container:
       image: php:${{ matrix.php-version }}-fpm
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: setup composer
         run: |
           curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer \
@@ -75,7 +75,7 @@ jobs:
     container:
       image: mcr.microsoft.com/devcontainers/php:2-8.2-bullseye
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: install scoper
         run: |