fix: specify bash shell for Windows compatibility in unit-tests

- Add 'shell: bash' to the coverage test step in unit-tests job
- Fixes PowerShell parser error on Windows runners: 'Missing ( after if'
- Bash syntax [[ ]] requires bash shell, not PowerShell default on Windows
- Ensures cross-platform compatibility for conditional coverage logic

Author: codcod

.github/workflows/ci.yml

@@ -181,6 +181,7 @@ jobs:
       - name: Run tests with coverage
         env:
           PYTHONPATH: ${{ github.workspace }}/src
+        shell: bash
         run: |
           if [[ "${{ matrix.coverage }}" == "true" ]]; then
             uv run python -m pytest tests/ \