Update actions/checkout action to v5 (#62)

| datasource  | package          | from | to |
| ----------- | ---------------- | ---- | -- |
| github-tags | actions/checkout | v4   | v5 |

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
         php-version:
           - "8.3"
     steps:
-      - uses: "actions/checkout@v4"
+      - uses: "actions/checkout@v5"
       - uses: "shivammathur/setup-php@v2"
         with:
           coverage: "none"
@@ -47,7 +47,7 @@ jobs:
             code-coverage: "pcov"
 
     steps:
-      - uses: "actions/checkout@v4"
+      - uses: "actions/checkout@v5"
       - uses: "shivammathur/setup-php@v2"
         with:
           coverage: "${{ matrix.code-coverage }}"
@@ -80,7 +80,7 @@ jobs:
           - "8.3"
 
     steps:
-      - uses: "actions/checkout@v4"
+      - uses: "actions/checkout@v5"
       - uses: "shivammathur/setup-php@v2"
         with:
           coverage: "none"
@@ -99,7 +99,7 @@ jobs:
           - "8.3"
 
     steps:
-      - uses: "actions/checkout@v4"
+      - uses: "actions/checkout@v5"
       - uses: "shivammathur/setup-php@v2"
         with:
           coverage: "none"