Bump flask from 1.1.2 to 2.0.1

Bumps [flask](https://github.com/pallets/flask) from 1.1.2 to 2.0.1.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](https://github.com/pallets/flask/compare/1.1.2...2.0.1)

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -1,7 +1,7 @@
 certifi==2021.5.30
 babel==2.9.1
 flask-babel==2.0.0
-flask==1.1.2
+flask==2.0.1
 jinja2==3.0.1
 lxml==4.6.3
 pygments==2.9.0