Bump actions/checkout from 2 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v4)

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

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

.github/workflows/autodoc.yml

@@ -13,7 +13,7 @@ jobs:
     if: github.event.pull_request.merged == true
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Process markdown files
         run: |
           find . -name '*.md' | xargs perl tools/autodoc.pl

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
     name: Go ${{ matrix.go }} test
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Check documentation generator
         run: |
           find . -name '*.md' | xargs env AUTODOC_DRYRUN=1 perl tools/autodoc.pl

.github/workflows/lint.yml

@@ -8,7 +8,7 @@ jobs:
       matrix:
         go: [1.19]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
         with:
           go-version: ${{ matrix.go }}