Bump actions/upload-artifact from 3 to 4 (#932)

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/documentation.yaml

@@ -45,7 +45,7 @@ jobs:
             DocMeta.setdocmeta!(DFTK, :DocTestSetup, :(using DFTK); recursive=true)
             doctest(DFTK)'
       - name: Upload Docs
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: documentation
           path: docs/build