install deps

Author: phw

.github/workflows/build.yaml

@@ -50,6 +50,8 @@ jobs:
       with:
         python-version: 3.9
         cache: 'pip'
+    - name: Install dependencies
+      run: pip install build
     - name: Build
       run: python -m build --sdist .
     - name: Publish package distributions to PyPI