Add better error handling for coinbase in starknet_deployments.py

[donatik27]

Description

This PR improves error handling and logging when getting the coinbase address in starknet deployments. Added detailed error logging to help diagnose issues during deployment.

Changes

File: kakarot_scripts/deployment/starknet_deployments.py

Old code:

New code:

Why these changes are needed

1. Better error diagnostics - Now we can see the actual error message if coinbase retrieval fails
2. Improved debugging - Makes it easier to identify and fix issues during deployment
3. Better logging - Provides more context about what went wrong instead of silently failing

Testing

• Tested deployment with valid coinbase
• Tested error handling with invalid coinbase
• Verified error messages are properly logged