switch linting tox env to use pre-commit, clean out travis linting env as unneeded

.pre-commit-config.yaml

@@ -19,3 +19,11 @@ repos:
     rev: v1.2.0
     hooks:
     - id: pyupgrade
+-   repo: local
+    hooks:
+    -   id: rst
+        name: rst
+        entry: python scripts/check-rst.py
+        language: python
+        additional_dependencies: [pygments, restructuredtext_lint]
+        python_version: python3.6

.travis.yml

@@ -13,7 +13,7 @@ env:
     # coveralls is not listed in tox's envlist, but should run in travis
     - TOXENV=coveralls
     # note: please use "tox --listenvs" to populate the build matrix below
-    - TOXENV=linting
+    # please remove the linting env in all cases
     - TOXENV=py27
     - TOXENV=py34
     - TOXENV=py36

tox.ini

@@ -38,15 +38,9 @@ commands =
 [testenv:linting]
 skipsdist = True
 usedevelop = True
-basepython = python2.7
+basepython = python3.6
-deps =
+deps = pre-commit
-    flake8
+commands = pre-commit run --all-files
-    # pygments required by rst-lint
-    pygments
-    restructuredtext_lint
-commands =
-    flake8 pytest.py _pytest testing setup.py pytest.py
-    {envpython} scripts/check-rst.py
 
 [testenv:py27-xdist]
 deps =