build(deps): bump insightsengineering/r-pkgdown-multiversion from 2 to 3

Bumps [insightsengineering/r-pkgdown-multiversion](https://github.com/insightsengineering/r-pkgdown-multiversion) from 2 to 3.
- [Release notes](https://github.com/insightsengineering/r-pkgdown-multiversion/releases)
- [Commits](insightsengineering/r-pkgdown-multiversion@v2...v3)

---
updated-dependencies:
- dependency-name: insightsengineering/r-pkgdown-multiversion
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/pkgdown-multi.yml

@@ -353,7 +353,7 @@ jobs:
         shell: bash
 
       - name: Create and publish docs ↗️
-        uses: insightsengineering/r-pkgdown-multiversion@v2
+        uses: insightsengineering/r-pkgdown-multiversion@v3
         with:
           path: ${{ github.event.repository.name }}
           default-landing-page: ${{ env.default-landing-page }}