Adapt to changes in v4.4 of actions/upload-artifact

actions/upload-artifact added in v4.4 a [breaking change](https://github.com/actions/upload-artifact/releases/tag/v4.4.0) by excluding hidden files by default. Unfortunately all coverage files are hidden files so the aggregation of coverage data failed.

Author: dalito

.github/workflows/ci.yml

@@ -49,6 +49,7 @@ jobs:
     - name: Upload coverage data
       uses: actions/upload-artifact@50769540e7f4bd5e21e526ee35c689e35e0d6874
       with:
+        include-hidden-files: true
         name: coverage-data-${{ matrix.python-version }}
         path: .coverage.*