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/main.yml

@@ -34,7 +34,7 @@ jobs:
       run: |
         $SPHINX -d _build/doctrees/ doc/ _build/html/ -b html
     - name: Upload error log
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       if: failure()
       with:
         name: build-log
@@ -43,7 +43,7 @@ jobs:
       run: |
         $SPHINX -d _build/doctrees/ doc/ _build/linkcheck/ -b linkcheck
     - name: Upload linkcheck results
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       if: ${{ success() || failure() }}
       with:
         name: linkcheck