ci: update tox.ini and add a gitlab-ci

.gitlab-ci.yml

+---
+default:
+  image: python:3.7
+
+include:
+  - project: "open-source/gitlab-ci-templates"
+    ref: "branch/default"
+    file:
+      - "templates/no-duplicated-ci-pipelines.yml"  # use workflow to avoid duplicated pipelines
+      - "templates/lint/flake8.yml"  # will do the equivalent of 'tox -e flake8'
+      - "templates/lint/black.yml"  # will do the equivalent of 'tox -e black'
+      - "templates/lint/check-manifest.yml"  # will do the equivalent of 'tox -e check-manifest'
+      # - "templates/lint/yamllint.yml"  # will do the equivalent of 'tox -e yamllint'
+      - "templates/tests/py3.yml"  # will do the equivalent of 'tox -e py3'
+      - "templates/create-release-on-heptapod.yml"  # this will create a release on heptapod
+      - "templates/upload-to-pypi.yml"  # on a new mercurial tag (expected to be done with release-new), will push a release on pypi
+  # uncomment and uses to customize/extend the configuration here if needed
+  # (it needs to be at the same level than "- project")
+  # - ".gitlab-ci-extended.yml"
+
+stages:
+  - lint
+  - tests
+  - release
+  - publish

tox.ini

 [tox]
-envlist = py27,py34,flake8
+envlist = py3,flake8,black,check-manifest,yamllint
 
 [testenv]
-sitepackages = true
 deps =
+  webtest
   pytest
-  https://hg.logilab.org/review/cubicweb/archive/cd16d2458da9.tar.bz2#egg=cubicweb
+  git+https://github.com/psycojoker/pytest-capture-deprecatedwarnings
 commands =
-  {envpython} -m pytest test {posargs}
+  {envpython} -m pytest {posargs:--verbose}
+
+[pytest]
+python_files = *test_*.py
+testpaths = test
+addopts = -r fEs
 
 [testenv:flake8]
+basepython = python3
 skip_install = true
-whitelist_externals =
-  flake8
 deps =
   flake8
 commands = flake8
 
 [flake8]
-exclude = cubicweb_dataprocessing/migration/*,test/data/*,setup.py,.tox/*
+exclude = cubicweb_dataprocessing/migration/*,.tox/*
+format = pylint
+ignore = W503, E203, E731, E231
 max-line-length = 100
 
-[pytest]
-python_files = *test_*.py
+[testenv:black]
+basepython = python3
+skip_install = true
+deps =
+  black >= 19.10b0
+commands = black --check .
+
+[testenv:black-run]
+basepython = python3
+skip_install = true
+deps =
+  black >= 19.10b0
+commands = black .
 
+[testenv:check-manifest]
+skip_install = true
+deps =
+  check-manifest
+commands =
+  {envpython} -m check_manifest {toxinidir}
+
+[testenv:pypi-publish]
+basepython = python3
+skip_install = true
+whitelist_externals = rm
+deps =
+  twine
+passenv =
+  TWINE_USERNAME
+  TWINE_PASSWORD
+commands =
+  rm -rf build dist .egg .egg-info
+  python3 setup.py sdist bdist_wheel
+  twine check dist/*
+  twine upload --skip-existing dist/*