Update requirements.txt

[spriyabrat]

I encountered the error as my docker container got exited after creating it from docker image.

After checking the docker logs I found the below error;

634c41109fd3 flaskapp:latest "python app.py" About a minute ago Exited (1) About a minute ago practical_wilbur
ubuntu@ip-172-31-92-203:~/two-tier-flask-app$ docker logs 634c
Traceback (most recent call last):
File "/app/app.py", line 2, in
from flask import Flask, render_template, request, redirect, url_for
File "/usr/local/lib/python3.9/site-packages/flask/init.py", line 7, in
from .app import Flask as Flask
File "/usr/local/lib/python3.9/site-packages/flask/app.py", line 28, in
from . import cli
File "/usr/local/lib/python3.9/site-packages/flask/cli.py", line 18, in
from .helpers import get_debug_flag
File "/usr/local/lib/python3.9/site-packages/flask/helpers.py", line 16, in
from werkzeug.urls import url_quote
ImportError: cannot import name 'url_quote' from 'werkzeug.urls' (/usr/local/lib/python3.9/site-packages/werkzeug/urls.py

After adding the "Werkzeug==2.0.1" in requirement.txt file,the issue got resolved.
So kindly review this and accept my pull request, if necessary.