Fix GH Actions config

Author: sanmai

.github/workflows/cs.yaml

@@ -17,7 +17,7 @@ jobs:
     name: PHP ${{ matrix.php-version }}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2

.github/workflows/mt.yaml

@@ -19,7 +19,7 @@ jobs:
     name: PHP ${{ matrix.php-version }} ${{ matrix.dependencies }}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2

.github/workflows/tests.yaml

@@ -23,7 +23,7 @@ jobs:
     name: PHP ${{ matrix.php-version }} ${{ matrix.legend }}
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2