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Fix naming of flake8 config file

.flake8

@@ -0,0 +1,3 @@
+[flake8]
+max-line-length = 119
+ignore = E9,F63,F7,F82,E402

.github/workflows/python-non-master.yml

@@ -5,6 +5,9 @@ on:
     branches:
       - '*'
       - '!master'
+  pull_request:
+    branches:
+      - 'master'
 
 jobs:
   build: