chore: bump `actions/checkout` to v4

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

@@ -6,7 +6,7 @@ jobs:
   R-CMD-check:
     runs-on: macOS-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: r-lib/actions/setup-r@v2-branch
       - name: Install dependencies
         run: |
@@ -17,4 +17,4 @@ jobs:
         env:
           _R_CHECK_FORCE_SUGGESTS_: true
         run: rcmdcheck::rcmdcheck(args = "--no-manual", error_on = "error")
-        shell: Rscript {0}
+        shell: Rscript {0}