[Maint] use correct coverage upload

Author: RDoerfel

.github/workflows/ci.yml

@@ -31,10 +31,8 @@ jobs:
       run: |
         pytest test/ --cov=plotting --cov-report=xml --cov-report=term-missing
     
-    - name: Upload coverage to Codecov
-      uses: codecov/codecov-action@v3
+    - name: Upload coverage reports to Codecov
+      uses: codecov/codecov-action@v5
       with:
-        file: ./coverage.xml
-        flags: unittests
-        name: codecov-umbrella
-        fail_ci_if_error: false
+        token: ${{ secrets.CODECOV_TOKEN }}
+        slug: RDoerfel/plotting