github-actions(deps): bump actions/download-artifact from 3 to 4

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

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

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

.github/workflows/ci-docs.yml

@@ -100,7 +100,7 @@ jobs:
       run: git fetch origin +refs/tags/*:refs/tags/*
 
     - name: Download branch docs
-      uses: actions/download-artifact@v3
+      uses: actions/download-artifact@v4
       with:
         name: Documentation-${{ matrix.os }}-${{ matrix.python-version }}-x64
         path: _built_docs/${{ github.ref }}
@@ -115,7 +115,7 @@ jobs:
       if: github.ref == 'refs/heads/main'
 
     - name: Download main docs
-      uses: actions/download-artifact@v3
+      uses: actions/download-artifact@v4
       with:
         name: Documentation-${{ matrix.os }}-${{ matrix.python-version }}-x64
         path: _built_docs/${{ github.ref }}