Install numpy for unit test in GitHub Action.

.github/workflows/packaging.yml

@@ -70,6 +70,9 @@ jobs:
       - name: Install the wheel
         run: python -m pip install ${{ steps.find_sdist_filename.outputs.filename }}
 
+      - name: Install numpy for unit test
+        run: python -m pip install numpy
+
       - name: Run python unit tests
         run: pytest
 
@@ -123,7 +126,7 @@ jobs:
           # skip musllinux: build takes too long with default os images.
           CIBW_SKIP: 'pp* *musllinux*'
           CIBW_BUILD: '${{ matrix.python_version }}-*'
-          CIBW_TEST_REQUIRES: pytest
+          CIBW_TEST_REQUIRES: pytest numpy
           CIBW_TEST_COMMAND: pytest {package}/test
         run: python -m cibuildwheel ${{ steps.find_sdist_filename.outputs.filename }}