build(deps): bump actions/checkout from 3 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...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] <[email protected]>

Author: dependabot[bot]

.github/workflows/frontend-regression-tests.yml

@@ -13,7 +13,7 @@ jobs:
         run:
             working-directory: frontend
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v6
     - name: Use Node.js 22.x
       uses: actions/setup-node@v3
       with: