CI: install needed flake8 helper packages

Author: ctrueden

.github/workflows/build.yml

@@ -61,7 +61,7 @@ jobs:
 
       - name: Flake code
         run: |
-          python -m pip install flake8
+          python -m pip install flake8 Flake8-pyproject flake8-typing-imports
           python -m flake8 src tests
 
       - name: Check import ordering