`_pickle.UnpicklingError: pickle data was truncated` raised in database session using MySql

[Lin-Nikaido]

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Describe the bug
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When put leage data into event and load it. the _pickle.UnpicklingError was occurred.
The root caurse is DynamicPickleType mapping BLOB as default in case of MySql, not LONGBLOB. And learge data will be able to cut off tail of data. And raise pickle error.

To Reproduce
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1. Install '...'
2. Run '....'
3. Open '....'
4. See error

Expected behavior
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Desktop (please complete the following information):

• OS: AL2023
• Python version(python -V): 3.10
• ADK version(pip show google-adk): 1.13.0

Additional context
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