ignore undefined variables since PythonCall defines some of them

Author: Christopher Doris

.github/workflows/tests.yml

@@ -69,7 +69,7 @@ jobs:
       - name: Lint with flake8
         run: |
           # stop the build if there are Python syntax errors or undefined names
-          flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+          flake8 . --count --select=E9,F63,F7,F82 --ignore=F821 --show-source --statistics
           # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
           flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
       - name: Run tests