Bump actions/checkout from 6 to 7

Bumps [actions/checkout](https://github.com/actions/checkout) from 6 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v6...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/php-cs-fixer.yml

@@ -8,7 +8,7 @@ jobs:
 
         steps:
             - name: Checkout code
-              uses: actions/checkout@v6
+              uses: actions/checkout@v7
               with:
                   ref: ${{ github.head_ref }}
 

.github/workflows/tests.yml

@@ -16,7 +16,7 @@ jobs:
 
         steps:
             -   name: Checkout code
-                uses: actions/checkout@v6
+                uses: actions/checkout@v7
 
             -   name: Install optimizers
                 run: |

.github/workflows/update-changelog.yml

@@ -10,7 +10,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           ref: main