Formatting: Format all python code with black.

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BUG=b:233893248
TEST=CQ

Change-Id: I66591d7a738d241aed3290138c0f68065ab10a6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3879174
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Alex Klein <saklein@chromium.org>
diff --git a/api/controller/__init__.py b/api/controller/__init__.py
index 05fa750..b3191d4 100644
--- a/api/controller/__init__.py
+++ b/api/controller/__init__.py
@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-IMPORT_PATTERN = 'chromite.api.controller.%s'
+IMPORT_PATTERN = "chromite.api.controller.%s"
 
 # Endpoint ran successfully.
 RETURN_CODE_SUCCESS = 0