Update to Jira Connect App qsh verification

Atlassian is introducing a breaking change to address a security vulnerability:

Action required: Atlassian Connect vulnerability allows bypass of app qsh verification via context JWTs

It looks like our app is affected because we are using JWT authentication. We do verify the qsh claim but we should still follow the steps described here.

Setting priority2 because the change will be enforced by Jun 7, 2021.