chore(deps-dev): Update flask requirement from >=1.1 to >=3.1.3

Updates the requirements on [flask](https://github.com/pallets/flask) to permit the latest version.
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](pallets/flask@1.1.0...3.1.3)

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

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

Author: dependabot[bot]

dev-requirements.txt

@@ -11,7 +11,7 @@ opentelemetry-instrumentation-grpc
 httpx>=0.28.1
 pyOpenSSL>=26.0.0
 # needed for type checking
-Flask>=1.1
+Flask>=3.1.3
 # needed for auto fix
 ruff===0.14.1
 # needed for .env file loading in examples