ci(deps): bump actions/checkout from 2 to 5

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/R-CMD-check.yaml

@@ -30,7 +30,7 @@ jobs:
       R_KEEP_PKG_SOURCE: yes
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - uses: r-lib/actions/setup-pandoc@v2
 

.github/workflows/docker-image.yml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: Check Out Repo
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - id: string
         uses: ASzc/change-string-case-action@v6

.github/workflows/pkgdown.yaml

@@ -23,7 +23,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - uses: r-lib/actions/setup-pandoc@v2