chore(deps): bump boto3 in /examples/chatbots/python

Bumps [boto3](https://github.com/boto/boto3) from 1.39.8 to 1.40.15.
- [Release notes](https://github.com/boto/boto3/releases)
- [Commits](boto/boto3@1.39.8...1.40.15)

---
updated-dependencies:
- dependency-name: boto3
  dependency-version: 1.40.15
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

examples/chatbots/python/requirements.txt

@@ -1,5 +1,5 @@
 aiobotocore[boto3]==2.23.2
-boto3==1.39.8
+boto3==1.40.15
 mcp==1.12.3
 uvicorn==0.35.0