Bump actions/checkout version

Author: W0rma

.github/workflows/main.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
 
     - name: Setup PHP
       uses: shivammathur/setup-php@v2