Workflows: Avoid the noisy style checker

Replace the style checker with a simpler syntax checker. For example, if
I added a "k" before "import" in pw_poller.py:

./pw_poller.py:7:9: E999 SyntaxError: invalid syntax
kimport configparser
        ^
1     E999 SyntaxError: invalid syntax
1

Signed-off-by: Kees Cook <[email protected]>

Author: kees

.github/workflows/lint.yml

@@ -3,9 +3,8 @@
 name: Lint checks
 on: [push, pull_request]
 jobs:
-  yapf:
+  lint:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - name: yapf
-      uses: AlexanderMelde/[email protected]
+    - uses: cclauss/Find-Python-syntax-errors-action@master