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

Bumps [boto3](https://github.com/boto/boto3) from 1.42.84 to 1.43.4.
- [Release notes](https://github.com/boto/boto3/releases)
- [Commits](boto/boto3@1.42.84...1.43.4)

---
updated-dependencies:
- dependency-name: boto3
  dependency-version: 1.43.2
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

examples/chatbots/python/requirements.txt

@@ -1,7 +1,7 @@
 strands-agents==1.38.0
 mcp==1.26.0
 uvicorn==0.46.0
-boto3==1.42.84
+boto3==1.43.4
 
 # For testing, this module is installed from local files.
 # Uncomment this line to build using the module from PyPi