GH-36750: [R] Fix test-r-devdocs on MacOS (#36751)

### Rationale for this change

The test-r-devdocs job is failing. It is failing because we are pinning a version of R that is so old that CRAN no longer serves binaries (#31757), so some of the package builds are failing.

### What changes are included in this PR?

Use the `setup-r-dependencies` action which either installs the correct build dependencies or uses older binary versions to avoid building from source (or both).

### Are these changes tested?

Yes, as part of the test-r-devdocs job.

### Are there any user-facing changes?

No.
* Closes: #36750

Authored-by: Dewey Dunnington <dewey@voltrondata.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>

dev/tasks/r/github.devdocs.yml

@@ -38,10 +38,9 @@ jobs:
           # remove after https://issues.apache.org/jira/browse/ARROW-16376
           r-version: '4.1'
       - uses: r-lib/actions/setup-pandoc@v2
-      - name: Install knitr, rmarkdown
-        run: |
-          install.packages(c("rmarkdown", "knitr", "sessioninfo"))
-        shell: Rscript {0}
+      - uses: r-lib/actions/setup-r-dependencies@v2
+        with:
+          packages: "rmarkdown, knitr, sessioninfo"
       - name: Session info
         run: |
           options(width = 100)