deps(a2a): upgrade a2a with db support

[jer96]

Description

Google recently updated the A2A SDK with DB support and this is a non-optional dependency. a2aproject/a2a-python#259.

When using A2A without this dependency the following error message is show:

E   ImportError: DatabaseTaskStore requires SQLAlchemy and a database driver. Install with one of: 'pip install a2a-sdk[postgresql]', 'pip install a2a-sdk[mysql]', 'pip install a2a-sdk[sqlite]', or 'pip install a2a-sdk[sql]'

Related Issues

Documentation PR

Type of Change

Dependency bump

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 run prepare

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary 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, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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