Fix bad import in calculator tool example

[dajulia3]

In the repo structure, the package is just called "agent_framework" ... this example is out of date. Maybe internally you guys have a repository that you pull from where you have the xrx_agent_framework package published, but in the OSS project the submodule structure just has an "agent_framework" directory in the xrx-core submodule.

It's not a big deal but it did make me question if there was some pypi package that I should reference instead of the submodule. So it's probably still worth correcting :).

[alessandro-neri]

Hello @dajulia3 and thank you for contributing.
Could you better explain the issue?

The name of the folder is "xrx_agent_framework" both in main and develop.
For this reason the import should be: from xrx_agent_framework import observability_decorator
I attached a screenshot below.