Bump actions/checkout from 3 to 4

Bumps [actions/checkout](/~https://github.com/actions/checkout) from 3 to 4.
- [Release notes](/~https://github.com/actions/checkout/releases)
- [Changelog](/~https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...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/deploy.yaml

@@ -14,7 +14,7 @@ jobs:
     steps:
       # Boilerplate
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       # We need Ghostscript for XeTeX tests.
       - run: sudo apt-get update && sudo apt-get install ghostscript
       - name: Install TeX Live

.github/workflows/main.yaml

@@ -12,7 +12,7 @@ jobs:
     steps:
       # Boilerplate
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       # We need Ghostscript for XeTeX tests.
       - run: sudo apt-get update && sudo apt-get install ghostscript
       - name: Install TeX Live