⬆️ Update actions/upload-artifact action to v4 (#28)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/tests.yaml

@@ -39,7 +39,7 @@ jobs:
       - name: 🚀 Run pytest
         run: poetry run pytest --cov src tests
       - name: ⬆️ Upload coverage artifact
-        uses: actions/upload-artifact@v3.1.3
+        uses: actions/upload-artifact@v4.1.0
         with:
           name: coverage-${{ matrix.python }}
           path: .coverage