chore: bump actions/checkout from 5 to 6 (#21)

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
                 php: [7.2]
         runs-on: ubuntu-latest
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - name: Setup PHP, with composer and extensions
               uses: shivammathur/setup-php@v2
@@ -44,7 +44,7 @@ jobs:
 
         runs-on: ubuntu-latest
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - name: Setup PHP, with composer and extensions
               uses: shivammathur/setup-php@v2