build(deps): 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/release.yml

@@ -20,12 +20,12 @@ jobs:
             fc-cache -f
             make doc
       - name: Upload bithesis.pdf for later usage.
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: bithesis
           path: bithesis.pdf
       - name: Upload *.cls for later usage.
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: cls
           path: "*.cls"