chore(deps): update dependency google-cloud-dialogflow-cx to v2 (#13603)

Author: renovate-bot

dialogflow-cx/requirements.txt

@@ -1,4 +1,4 @@
-google-cloud-dialogflow-cx==1.38.0
+google-cloud-dialogflow-cx==2.0.0
 Flask==3.0.3
 python-dateutil==2.9.0.post0
 functions-framework==3.9.2