chore: fix kokoro config for samples (#236)

Source-Link: https://github.com/googleapis/synthtool/commit/dd05f9d12f134871c9e45282349c9856fbebecdd
Post-Processor: gcr.io/repo-automation-bots/owlbot-python:latest@sha256:aea14a583128771ae8aefa364e1652f3c56070168ef31beb203534222d842b8b
diff --git a/.github/.OwlBot.lock.yaml b/.github/.OwlBot.lock.yaml
index d57f742..9ee60f7 100644
--- a/.github/.OwlBot.lock.yaml
+++ b/.github/.OwlBot.lock.yaml
@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:6186535cbdbf6b9fe61f00294929221d060634dae4a0795c1cefdbc995b2d605
+  digest: sha256:aea14a583128771ae8aefa364e1652f3c56070168ef31beb203534222d842b8b