Bump actions/checkout from 5 to 6 (#156)

Author: dependabot[bot]

.github/workflows/phpstan.yml

@@ -10,7 +10,7 @@ jobs:
 
     steps:
       - name: Startup
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Download PHP Release
         uses: dsaltares/fetch-gh-release-asset@1.1.2
         with: