Add dask installation to Codecov workflow

Author: brendancol

.github/workflows/codecov.yml

@@ -27,6 +27,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install -e .[tests]
+        pip install dask
     - name: Generate coverage report
       run: |
         NUMBA_DISABLE_JIT=1 pytest --cov=./ --cov-report=xml --ignore ./xrspatial/tests/test_polygonize.py