[bugfix] Fix multiple "updated_at" columns for media updates

[tsmethurst]

Description

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This pull request fixes an issue where the column updated_at was being passed into media attachment updates as an extra column. This was causing double updated_at columns to be used when making db queries. SQLite doesn't mind this, but postgres does.

closes #1645

Checklist

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[tsmethurst]

This is not really related to the PR, just a silly thing that tripped up the test.