Bump actions/upload-artifact from 3 to 4

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v3...v4)

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

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

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

@@ -98,7 +98,7 @@ jobs:
 
       - name: Upload check results
         if: failure()
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: wsl-backend-results
           path: check

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

@@ -113,7 +113,7 @@ jobs:
 
       - name: Upload check results
         if: failure()
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: ${{ runner.os }}-r${{ matrix.config.r }}-results
           path: check

.github/workflows/cmdstan-tarball-check.yaml

@@ -95,7 +95,7 @@ jobs:
 
       - name: Upload check results
         if: failure()
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: ${{ runner.os }}-r${{ matrix.config.r }}-results
           path: check