chore: add prerelease nox session (#347)

Source-Link: googleapis/synthtool@d2871d9
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:b2dc5f80edcf5d4486c39068c9fa11f7f851d9568eea4dcba130f994ea9b5e97

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: gcf-owl-bot[bot]

packages/google-cloud-securitycenter/.github/.OwlBot.lock.yaml

@@ -13,5 +13,5 @@
 # limitations under the License.
 docker:
   image: gcr.io/cloud-devrel-public-resources/owlbot-python:latest
-  digest: sha256:65e656411895bff71cffcae97246966460160028f253c2e45b7a25d805a5b142
-# created: 2022-06-12T13:11:45.905884945Z
+  digest: sha256:b2dc5f80edcf5d4486c39068c9fa11f7f851d9568eea4dcba130f994ea9b5e97
+# created: 2022-06-12T16:09:31.61859086Z

packages/google-cloud-securitycenter/noxfile.py

@@ -20,6 +20,7 @@
 
 import os
 import pathlib
+import re
 import shutil
 import warnings