Code clean-up using black and flake8

 - No functional change

Signed-off-by: Tim Hall <tim.hall@arm.com>
Change-Id: I5ab1198b9d092cd041fa9b85b2dee9900d299bfc
diff --git a/ethosu/vela/mark_tensors.py b/ethosu/vela/mark_tensors.py
index b557f90..72ab8cf 100644
--- a/ethosu/vela/mark_tensors.py
+++ b/ethosu/vela/mark_tensors.py
@@ -112,7 +112,9 @@
     ),
     (
         set(("Conv2DBackpropInputSwitchedBias",)),
-        purpose_from_list([TensorPurpose.FeatureMap, TensorPurpose.Weights, TensorPurpose.FeatureMap, TensorPurpose.FeatureMap]),
+        purpose_from_list(
+            [TensorPurpose.FeatureMap, TensorPurpose.Weights, TensorPurpose.FeatureMap, TensorPurpose.FeatureMap]
+        ),
     ),
     (
         set(("QuantizedConv2D", "QuantizedMatMul")),