update checkout to v3

Author: ariaieboy

.github/workflows/psalm.yml

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