fix: push the coverage report to codecov

.github/workflows/unit.yaml

@@ -67,3 +67,22 @@ jobs:
         run: pip install nox
       - name: Test with pytest
         run: nox -s ci_test
+      - uses: actions/upload-artifact@v4
+        if: ${{ matrix.python-version == '3.10' }}
+        with:
+          name: coverage
+          path: coverage.xml
+
+  coverage:
+    needs: [build]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          name: coverage
+          path: coverage.xml
+      - name: codecov
+        uses: codecov/codecov-action@v4
+        with:
+          file: ./coverage.xml
+          token: ${{ secrets.CODECOV_TOKEN }}