Moved tool_spec retrieval to after the before model invocation callback

[pghazanfari]

Description

Related Issues

Documentation PR

This shouldn't require a documentation changes.

Type of Change

Other (please describe): Moved the tool_spec retrieval in the event_loop to be AFTER the before model invocation callback. The reason behind this is that I have a use case for dynamically swapping the tools available for the model in-between each event loop iteration. I'd like to use the before model invocation event callback to make this happen.

Testing

How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

I ran hatch test and everything succeeded.

• I ran hatch run prepare

Checklist

• I have read the CONTRIBUTING document
• [N/A] I have added any necessary tests that prove my fix is effective or my feature works
• [N/A] I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• [N/A] Any dependent changes have been merged and published

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