Fixes tox syntax error

tox.ini

@@ -22,7 +22,7 @@ deps=
     pypy,pypy3: -r{toxinidir}/requirements/test-ci-base.txt
 
     linkcheck,apicheck,configcheck: -r{toxinidir}/requirements/docs.txt
-    flake8,flakeplus,pydocstyle -r{toxinidir}/requirements/pkgutils.txt
+    flake8,flakeplus,pydocstyle: -r{toxinidir}/requirements/pkgutils.txt
 sitepackages = False
 recreate = False
 commands = pip install -U -r{toxinidir}/requirements/dev.txt