[fix] #59 fix Python version in gitlab-ci

use Python 3.6.4
5 jobs for graphql in 5 minutes and 3 seconds (queued for 1 minute and 20 seconds)
latest
Status Job ID Name Coverage
  Format
passed #33443
redshift-docker-python
format

00:01:36

 
  Test
passed #33445
redshift-docker-python
check

00:02:28

passed #33444
redshift-docker-python
test

00:00:48

 
  Build
passed #33446
redshift-docker-python
build

00:00:56

 
  Release
manual #33447
redshift-docker-python allowed to fail manual
release_test