ci skip : Move flake8 to static analysis group

Signed-off-by: Aleksei Stepanov <penguinolog@gmail.com>

(cherry picked from commit 2127845)
Signed-off-by: Aleksei Stepanov <penguinolog@gmail.com>

Author: penguinolog

.travis.yml

@@ -78,14 +78,14 @@ jobs:
     - pip install --upgrade "mypy >= 0.630"
     script:
     - mypy --strict advanced_descriptors
-
-  - <<: *code_style_check
+  - <<: *static_analysis
     name: "PEP8"
     install:
     - *upgrade_python_toolset
     - pip install --upgrade flake8
     script:
     - flake8
+
   - <<: *code_style_check
     name: "PEP257"
     install: