chore(deps): bump flask from 2.3.2 to 3.1.3 in /example/flask

Bumps [flask](https://github.com/pallets/flask) from 2.3.2 to 3.1.3.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](pallets/flask@2.3.2...3.1.3)

---
updated-dependencies:
- dependency-name: flask
  dependency-version: 3.1.3
  dependency-type: direct:production
...

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

Author: dependabot[bot]

example/flask/requirements.txt

@@ -1,5 +1,5 @@
 uptrace==1.17.1
-flask==2.3.2
+flask==3.1.3
 flask_sqlalchemy==2.5.1
 itsdangerous==2.1.2
 opentelemetry-instrumentation-flask==0.38b0