Bump flask from 1.1.2 to 2.0.0 in /integration/examples

Bumps [flask](https://github.com/pallets/flask) from 1.1.2 to 2.0.0.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](pallets/flask@1.1.2...2.0.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

integration/examples/buildpacks-python/requirements.txt

@@ -1 +1 @@
-Flask==1.1.2
+Flask==2.0.0