Lower Black target version to workaround Black bug

Author: jdufresne

Makefile

@@ -2,12 +2,12 @@
 
 style:
 	isort -rc debug_toolbar example tests
-	black --target-version py35 debug_toolbar example tests setup.py
+	black --target-version=py34 debug_toolbar example tests setup.py
 	flake8 debug_toolbar example tests
 
 style_check:
 	isort -rc -c debug_toolbar example tests
-	black --target-version py35 --check debug_toolbar example tests setup.py
+	black --target-version=py34 --check debug_toolbar example tests setup.py
 
 flake8:
 	flake8 debug_toolbar example tests

debug_toolbar/panels/cache.py

@@ -180,7 +180,7 @@ def _store_call_info(
         trace=None,
         template_info=None,
         backend=None,
-        **kw,
+        **kw
     ):
         if name == "get":
             if return_value is None: