build(deps): bump actions/checkout from 5 to 6 (#354)

Bumps [actions/checkout](https://github.com/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
...

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

Author: dependabot[bot]

.github/workflows/add-project.yml

@@ -9,7 +9,7 @@ jobs:
     if: ${{ !github.event.issue.pull_request && contains(github.event.issue.labels.*.name, 'add-project') && startsWith(github.event.comment.body, '/draft-pr') }}
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-python@v6
         with:
           python-version: "3.11"

.github/workflows/check.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Fetch projects.yaml
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           sparse-checkout: |
             projects.yaml

.github/workflows/deploy.yml

@@ -23,7 +23,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Fetch README
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           sparse-checkout: |
             README.md

.github/workflows/sync-repo.yml

@@ -10,7 +10,7 @@ jobs:
     name: Sync to Gitee
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Push

.github/workflows/update-best-of-list.yml

@@ -30,7 +30,7 @@ jobs:
       - name: Set version via date
         if: ${{ ! (env.VERSION != null && env.VERSION != '') }}
         run: echo "VERSION=$(date '+%Y.%m.%d')" >> $GITHUB_ENV
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Append time to version if necessary
         shell: bash
         run: |