Only run pre-commit once

Author: skorokithakis

tox.ini

@@ -4,7 +4,7 @@
 # install tox" and then run "tox" from this directory.
 
 [tox]
-envlist = py26, py27, py32, py33, py34, py35, py36, py37, py38, pypy3, coverage, checks
+envlist = py26, py27, py32, py33, py34, py35, py36, py37, py38, pypy3, coverage
 
 [testenv]
 commands = py.test
@@ -18,11 +18,6 @@ commands = py.test --doctest-glob=README.rst  # test documentation
 deps = pytest
        mock
 
-[testenv:checks]
-basepython=python3
-commands = pre-commit run -a
-deps = pre-commit
-
 [testenv:coverage]
 basepython=python3
 commands = coverage erase