CI: Bump r-lib/actions from 1 to 2

Bumps [r-lib/actions](https://github.com/r-lib/actions) from 1 to 2.
- [Release notes](https://github.com/r-lib/actions/releases)
- [Commits](https://github.com/r-lib/actions/compare/v1...v2)

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

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

.github/workflows/manpages.yml

@@ -12,7 +12,7 @@ jobs:
     if: always() && github.repository == 'SerenityOS/serenity' && github.ref == 'refs/heads/master'
     steps:
       - uses: actions/checkout@v3
-      - uses: r-lib/actions/setup-pandoc@v1
+      - uses: r-lib/actions/setup-pandoc@v2
         with:
           pandoc-version: '2.13'
       - name: Actually build website