build(deps): bump actions/upload-artifact from 4 to 5 (#167)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4 to 5.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...v5)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/citation.yml

@@ -66,7 +66,7 @@ jobs:
           fi
       - name: Upload PDF
         if: always()
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: citation-preview.pdf
           path: citation-preview.pdf

.github/workflows/docs.yml

@@ -54,7 +54,7 @@ jobs:
           cp -a docs/_build/html artifact/povm-toolbox-htmldocs
       - name: Upload nice docs artifact
         if: always()
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: povm-toolbox-htmldocs
           path: ./artifact