Bump actions/checkout from 4.1.7 to 4.2.1 (#56)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4.1.7 to 4.2.1.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4.1.7...v4.2.1)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4.1.7
+        uses: actions/checkout@v4.2.1
         with:
           fetch-depth: 0
 

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

@@ -15,7 +15,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4.1.7
+        uses: actions/checkout@v4.2.1
         with:
           fetch-depth: 0
 

.github/workflows/publish-subsplits.yml

@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4.1.7
+        uses: actions/checkout@v4.2.1
         with:
           fetch-depth: 0
           persist-credentials: false

.github/workflows/static.yml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4.1.7
+        uses: actions/checkout@v4.2.1
         with:
           fetch-depth: 0