update_time defined twice hence removing once.

[PandasPirate]

Description of the change

a function was defined twice with same body. location is google.generativeai.types.file_types.File.update_time.

Motivation

It doesn't solve any specific problem but it cleans the code a bit

Type of change

Choose one: (Bug fix | Feature request | Documentation | Other)
other

Checklist

• I have performed a self-review of my code.
• I have added detailed comments to my code where applicable.
• I have verified that my change does not break existing code.
• My PR is based on the latest changes of the main branch (if unsure, please run git pull --rebase upstream main).
• I am familiar with the Google Style Guide for the language I have coded in.
• I have read through the Contributing Guide and signed the Contributor License Agreement.

[MarkDaoust]

Thanks!