add python:3.6 to test matrix in .gitlab-ci.yml

12 jobs for 43-add-python-3-6-to-gitlab-ci-yml in 13 minutes and 56 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Test
passed py3.5-min-mysql #19283

00:12:51

92.0%
passed py3.5-min-postgresql #19281

00:07:16

92.0%
passed py3.5-min-sqlite #19279

00:07:17

91.0%
passed py3.5-pypi-mysql #19284

00:07:31

92.0%
passed py3.5-pypi-postgresql #19282

00:07:21

92.0%
passed py3.5-pypi-sqlite #19280

00:07:21

91.0%
passed py3.6-min-mysql #19289

00:13:48

92.0%
passed py3.6-min-postgresql #19287

00:09:57

92.0%
passed py3.6-min-sqlite #19285

00:07:59

91.0%
passed py3.6-pypi-mysql #19290

00:10:09

92.0%
passed py3.6-pypi-postgresql #19288

00:09:59

92.0%
passed py3.6-pypi-sqlite #19286

00:10:07

91.0%