Bump actions/checkout from v4 to v5 (#902)

`actions/checkout@v4` runs on Node.js 20, which is deprecated in GitHub
Actions and will be forced to Node.js 24 by default on June 2nd, 2026.

## Changes

- Updated `actions/checkout@v4` → `actions/checkout@v5` across all
affected workflows:
  - `lint.yml`
  - `phpstan.yml`
  - `release.yml`
  - `continuous-integration.yml`
  - `style-check.yml`
  - `continuous-integration-32-bits.yml`
  - `update-changelog.yml`
  - `code-cov.yml`

`copilot-setup-steps.yml` was already on `v5` and required no change.

<!-- START COPILOT CODING AGENT TIPS -->
---

📍 Connect Copilot coding agent with [Jira](https://gh.io/cca-jira-docs),
[Azure Boards](https://gh.io/cca-azure-boards-docs) or
[Linear](https://gh.io/cca-linear-docs) to delegate work to Copilot in
one click without leaving your project management tool.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: DannyvdSluijs <618940+DannyvdSluijs@users.noreply.github.com>

Author: Copilot

.github/workflows/code-cov.yml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v4"
+        uses: "actions/checkout@v5"
 
       - name: "Install PHP"
         uses: "shivammathur/setup-php@v2"

.github/workflows/continuous-integration-32-bits.yml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v4"
+        uses: "actions/checkout@v5"
 
       - name: "Install PHP"
         uses: "shivammathur/setup-php@v2"

.github/workflows/continuous-integration.yml

@@ -34,7 +34,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v4"
+        uses: "actions/checkout@v5"
 
       - name: "Install PHP"
         uses: "shivammathur/setup-php@v2"

.github/workflows/lint.yml

@@ -23,7 +23,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v4"
+        uses: "actions/checkout@v5"
 
       - name: "Install PHP"
         uses: "shivammathur/setup-php@v2"

.github/workflows/phpstan.yml

@@ -25,7 +25,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v4"
+        uses: "actions/checkout@v5"
 
       - name: "Install PHP"
         uses: "shivammathur/setup-php@v2"

.github/workflows/release.yml

@@ -32,7 +32,7 @@ jobs:
 
         steps:
             - name: "Checkout"
-              uses: "actions/checkout@v4"
+              uses: "actions/checkout@v5"
               with:
                   ref: main
                   fetch-depth: 0

.github/workflows/style-check.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v4"
+        uses: "actions/checkout@v5"
 
       - name: "Install PHP"
         uses: "shivammathur/setup-php@v2"

.github/workflows/update-changelog.yml

@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v4"
+        uses: "actions/checkout@v5"
         with:
           ref: main
           fetch-depth: 0