ci: bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/cd-production.yml

@@ -60,7 +60,7 @@ jobs:
           echo "✅ Deploying from main branch"
 
       - name: Check recent commits
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 10
 
@@ -146,7 +146,7 @@ jobs:
       url: https://api.manacore.app
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup SSH
         uses: webfactory/ssh-agent@v0.9.0