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](https://github.com/actions/upload-artifact/compare/v3...v4)

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

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

.github/workflows/build_offline_docs.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Sphinx - Build HTML
         run: make SPHINXOPTS='--color' html
 
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: godot-docs-html-${{ matrix.branch }}
           path: _build/html
@@ -51,7 +51,7 @@ jobs:
 
           make SPHINXOPTS='--color' epub
 
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: godot-docs-epub-${{ matrix.branch }}
           path: _build/epub/GodotEngine.epub