chore(deps): bump actions/checkout in the github_actions group

Bumps the github_actions group with 1 update: [actions/checkout](https://github.com/actions/checkout).


Updates `actions/checkout` from 5 to 6
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
     container:
       image: python:${{ matrix.python-version }}-${{ matrix.debian-version }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install dependencies
         run: |
           apt-get update
@@ -44,7 +44,7 @@ jobs:
     container:
       image: python:3.14-trixie
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install nox
         run: pip install nox
       - name: Build docs
@@ -59,7 +59,7 @@ jobs:
     container:
       image: python:3.14-trixie
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install nox
         run: pip install nox
       - name: Run linter
@@ -74,7 +74,7 @@ jobs:
     container:
       image: node:22-trixie
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install standardjs dependencies
         run: make ci-install-standardjs
       - name: Run standardjs