chore(deps): update dependency google-cloud-dlp to v0.15.0 [(#3780)](GoogleCloudPlatform/python-docs-samples#3780)

Author: renovate-bot

samples/snippets/requirements.txt

@@ -1,4 +1,4 @@
-google-cloud-dlp==0.14.0
+google-cloud-dlp==0.15.0
 google-cloud-storage==1.28.0
 google-cloud-pubsub==1.4.3
 google-cloud-datastore==1.12.0