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] <[email protected]>

.github/workflows/scheduled.yml

@@ -30,7 +30,7 @@ jobs:
           python -m pytest -v --durations=0 --cov-report xml:cov.xml --cov-config=setup.cfg --cov=quadax/ --db ./prof.db
       - name: save coverage file and plot comparison results
         if: always()
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: unit_test_artifact
           path: |

.github/workflows/unittest.yml

@@ -42,7 +42,7 @@ jobs:
           python -m pytest -v --durations=0 --cov-report xml:cov.xml --cov-config=setup.cfg --cov=quadax/ --db ./prof.db
       - name: save coverage file and plot comparison results
         if: always()
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: unit_test_artifact
           path: |