style(callback_handler): fix docstring for PrintingCallbackHandler.__call__

[awsarron]

Description

fix docstring for PrintingCallbackHandler.__call__

resolves:

WARNING -  griffe: /Users/arron/.env/lib/python3.13/site-packages/strands/handlers/callback_handler.py:20: Parameter '-' does not appear in the function signature
WARNING -  griffe: /Users/arron/.env/lib/python3.13/site-packages/strands/handlers/callback_handler.py:21: Parameter '-' does not appear in the function signature
WARNING -  griffe: /Users/arron/.env/lib/python3.13/site-packages/strands/handlers/callback_handler.py:22: Parameter '-' does not appear in the function signature
WARNING -  griffe: /Users/arron/.env/lib/python3.13/site-packages/strands/handlers/callback_handler.py:23: Parameter '-' does not appear in the function signature

Type of Change

• Documentation update

Testing

• hatch fmt
• hatch run test-lint
• hatch test --all
• Ran mkdocs serve -a 0.0.0.0:8000 in the strands-agents/docs repository and verified that the griffe warning disappeared

Checklist

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

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.