build(deps): update flask requirement from ~=2.0.1 to ~=2.0.2

Updates the requirements on [flask](https://github.com/pallets/flask) to permit the latest version.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](pallets/flask@2.0.1...2.0.2)

---
updated-dependencies:
- dependency-name: flask
  dependency-type: direct:production
...

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

requirements.txt

@@ -5,7 +5,7 @@
 #
 # Use this to bust that cache: gcloud -q beta app deploy --no-cache ...
 git+https://github.com/snarfed/oauth-dropins.git#egg=oauth_dropins
-flask~=2.0.1
+flask~=2.0.2
 flask-caching~=1.10.1
 google-cloud-logging~=2.6.0
 gunicorn~=20.1