ci: update actions/checkout to v6

Author: stklcode

.github/workflows/phpstan.yml

@@ -8,7 +8,7 @@ jobs:
         php: [ '7.4', '8.0', '8.2', '8.4' ]
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Setup PHP
@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:
@@ -58,7 +58,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Setup PHP

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
     name: Push to stable
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Clean README.md
         run: tail -n +6 README.md > README.md.tmp && mv README.md.tmp README.md
       - name: WordPress.org plugin asset/readme update

.github/workflows/wordpress-plugin-asset-update.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Package plugin
         run: |

.github/workflows/wordpress-plugin-check.yml

@@ -9,7 +9,7 @@ jobs:
     name: New tag
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Clean README.md
         run: tail -n +6 README.md > README.md.tmp && mv README.md.tmp README.md
       - name: WordPress Plugin Deploy