style: add a few more checks

appveyor.yml

@@ -1,5 +1,5 @@
 environment:
-  # workaround an appveyor bug on macos 
+  # workaround an appveyor bug on macos
   # see https://github.com/appveyor/ci/issues/3376#issuecomment-611314299
   APPVEYOR_CONSOLE_DISABLE_PTY: true
   matrix:
@@ -11,8 +11,8 @@ environment:
       APPVEYOR_JOB_NAME: "python37-x64-macos-mojave"
 
 # while pypy libffi dependency is failing the build, allow failures on macos
-matrix:	
-  allow_failures:	
+matrix:
+  allow_failures:
     - APPVEYOR_BUILD_WORKER_IMAGE: macos-mojave
 
 stack: python 3.7