Switch to pytest flake execution

From separate flake run that people seem to not run on their local
machines simply merge it into one commit and make sure that if
anyone runs pytest they also see the flake failures

.travis.yml

@@ -35,7 +35,6 @@ install:
 script:
   - podman build -t $DIST -f test/Dockerfile-$DIST .
   - podman run -v $(pwd):/usr/src/rpmlint/ $DIST python3 -m pytest
-  - podman run -v $(pwd):/usr/src/rpmlint/ $DIST flake8
 
 after_success:
   - coverage combine

setup.cfg

@@ -10,4 +10,4 @@ import-order-style = google
 application-import-names = Testing
 
 [tool:pytest]
-addopts = -vv --cov=rpmlint -n auto
+addopts = -vv --cov=rpmlint -n auto --flake8