ci: bump actions

Author: JaZo

.github/workflows/phpstan.yml

@@ -11,7 +11,7 @@ jobs:
     name: phpstan
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2