Use actions/checkout@v4 (#309)

Author: Jubeki

.github/workflows/static-analysis.yml

@@ -21,7 +21,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2

.github/workflows/tests.yml

@@ -59,7 +59,7 @@ jobs:
           git config --global core.eol lf
 
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2