Update flask from 0.12 -> 1.1.2

[kodumbeats]

What does this PR do?

This PR updates Flask to a recent version, addressing the following bug with GET /__last_request__.

http-request-catcher runs on flask 0.12, and the is_xhr method, shown below` was deprecated and removed.

 File "/home/catcher/werkzeug/local.py", line 347, in __getattr__
   return getattr(self._get_current_object(), name)
AttributeError: 'Request' object has no attribute 'is_xhr'
172.17.0.1 - - [03/Jan/2021 14:18:14] "GET /__last_request__ HTTP/1.1" 500 -

Test Plan

• GET /__last_request__ returns null
• GET / returns 200
• GET /__last_request__ returns response

Related PRs and Issues

N/A

Have you read the Contributing Guidelines on issues?

Yes.