fix: Correct order of checks for environment variable keys, enabling Ollama defaults to work

[auphof]

This addresses #1584

• Moved the check for unnacepted_attributes to ensure it is evaluated after confirming the presence of key_name in the environment variable.
• This change improves the clarity and correctness of the environment variable handling logic, allowing the Ollama default env API_BASE to be handled in the Agent setup

[auphof]

I am not familiar with the testing of CrewAI, particularly as to where the appropriate test should be created , I am happy to create if someone could please point me in the correct direction

[auphof]

@joaomdmoura @bhancockio as you both worked in this area over the last week, please review or pass on appropriately the review of this PR #1591 together with #1589. Happy to assist where ever, Thank you for an awesome framework and that was a great interview with Matthew Berman https://x.com/joaomdmoura/status/1856384282475774441 👏👏👏