chore(python): add E231 to .flake8 ignore list (googleapis#440)

Source-Link: googleapis/synthtool@7ff4aad
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:462782b0b492346b2d9099aaff52206dd30bc8e031ea97082e6facecc2373244

Author: gcf-owl-bot[bot]

.flake8

@@ -16,7 +16,7 @@
 
 # Generated by synthtool. DO NOT EDIT!
 [flake8]
-ignore = E203, E266, E501, W503
+ignore = E203, E231, E266, E501, W503
 exclude =
   # Exclude generated code.
   **/proto/**

.github/.OwlBot.lock.yaml

@@ -13,4 +13,4 @@
 # limitations under the License.
 docker:
   image: gcr.io/cloud-devrel-public-resources/owlbot-python:latest
-  digest: sha256:7cffbc10910c3ab1b852c05114a08d374c195a81cdec1d4a67a1d129331d0bfe
+  digest: sha256:462782b0b492346b2d9099aaff52206dd30bc8e031ea97082e6facecc2373244