chore(deps): update dependency flask to v2.1.0 (#280)

Co-authored-by: Anthonios Partheniou <[email protected]>

Author: renovate-bot

Dialogflow-CX/requirements.txt

@@ -1,2 +1,2 @@
 google-cloud-dialogflow-cx==1.10.0
-Flask==2.0.3
+Flask==2.1.0