test: integrate mypy into tox.ini and gitlab-ci

.gitlab-ci.yml

@@ -27,6 +27,10 @@ flake8:
   stage: tests
   script: tox -e flake8
 
+mypy:
+  stage: tests
+  script: tox -e mypy
+
 trigger-other-pipelines:
   only:
     refs:

tox.ini

 [tox]
-envlist=py3,check-manifest,black
+envlist=py3,check-manifest,black,mypy
 
 [testenv]
 deps =
@@ -53,3 +53,8 @@ format = pylint
 ignore = W503, E203, E731, E231
 max-line-length = 100
 exclude = docs/*,.tox/*
+
+[testenv:mypy]
+deps =
+  mypy >= 0.761
+commands = mypy --ignore-missing-imports logilab/mtconverter/