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/ctags.yaml

@@ -8,7 +8,7 @@ jobs:
  name: Legacy ctags test
  runs-on: macos-latest
  steps:
- - uses: actions/checkout@v3
+ - uses: actions/checkout@v4
  with:
  fetch-depth: 0
  - name: Install brew packages and ensure legacy ctags
@@ -26,7 +26,7 @@ jobs:
  name: Exuberant ctags test
  runs-on: macos-latest
  steps:
- - uses: actions/checkout@v3
+ - uses: actions/checkout@v4
  with:
  fetch-depth: 0
  - name: Install brew packages and ensure exuberant ctags
@@ -44,7 +44,7 @@ jobs:
  name: Universal ctags test
  runs-on: macos-latest
  steps:
- - uses: actions/checkout@v3
+ - uses: actions/checkout@v4
  with:
  fetch-depth: 0
  - name: Install brew packages and ensure universal ctags

.github/workflows/publish.yaml

@@ -12,7 +12,7 @@ jobs:
  runs-on: macos-latest
  steps:
  - name: Checkout repository
- uses: actions/checkout@v2
+ uses: actions/checkout@v4
 
  - name: Install mdbook
  run: brew install mdbook

.github/workflows/release-pypi.yaml

@@ -15,7 +15,7 @@ jobs:
  id-token: write
  contents: write
  steps:
- - uses: actions/checkout@v2
+ - uses: actions/checkout@v4
  - name: Install dependencies
  run: python3 -m pip install --upgrade pip build setuptools wheel twine
  - name: Build pip package

.github/workflows/release.yaml

@@ -18,7 +18,7 @@ jobs:
  contents: write
  steps:
  - name: Checkout code
- uses: actions/checkout@v2
+ uses: actions/checkout@v4
  - name: Get version
  run: |
  # The environment variable GITHUB_REF is refs/tags/viewer-*

.github/workflows/run-differential-tests.yaml

@@ -12,7 +12,7 @@ jobs:
  matrix:
  python-version: [ '3.8', '3.9', '3.10' ]
  steps:
- - uses: actions/checkout@v3
+ - uses: actions/checkout@v4
  with:
  fetch-depth: 0
  - name: Set up Python