Create build dir before runnint GitHub actions

Author: canepan

.github/workflows/python-package.yml

@@ -38,5 +38,6 @@ jobs:
 #        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=120 --statistics
     - name: Test with tox or pytest
       run: |
+        mkdir -p build
         if [ -f tox.ini ]; then tox ; else pytest; fi