Update actions/checkout action to v4

| datasource  | package          | from | to |
| ----------- | ---------------- | ---- | -- |
| github-tags | actions/checkout | v3   | v4 |

Author: renovate[bot]

.github/workflows/continuous-integration.yml

@@ -52,7 +52,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v3"
+        uses: "actions/checkout@v4"
         with:
           fetch-depth: 0
 
@@ -104,7 +104,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v3"
+        uses: "actions/checkout@v4"
         with:
           fetch-depth: 0
 

.github/workflows/release-on-milestone-closed.yml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v3"
+        uses: "actions/checkout@v4"
 
       - name: "Release"
         uses: "laminas/automatic-releases@v1"

.github/workflows/release-phar.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v3"
+        uses: "actions/checkout@v4"
 
       - name: "Install PHP"
         uses: "shivammathur/[email protected]"