Fix isort warning

Author: rpkilby

tox.ini

@@ -43,7 +43,7 @@ deps =
     https://github.com/tomchristie/django-rest-framework/archive/master.tar.gz
 
 [testenv:isort]
-commands = isort --recursive --check-only rest_framework_filters tests {posargs:--diff}
+commands = isort --check-only rest_framework_filters tests {posargs:--diff}
 deps = isort
 
 [testenv:lint]