Un-pin upload-artifact action and enable include-hidden-files option

The `include-hidden-files` setting is required in future releases of this action
to enable uploading files whose names begin with a period.  We pinned the action
previously because this config option was broken when initially added, but it
has now been fixed.

See https://github.com/actions/upload-artifact/releases/tag/v3.2.1-node20.

.github/workflows/ci.yml

@@ -97,10 +97,11 @@ jobs:
  env:
  COVERAGE_FILE: .coverage.${{ matrix.python-version }}
  - name: Upload coverage file
- uses: actions/upload-artifact@v3.1.3
+ uses: actions/upload-artifact@v3
  with:
  name: coverage
  path: .coverage.*
+ include-hidden-files: true
  Coverage:
  needs: tests
  runs-on: ubuntu-latest