First retains stale *time.Time when reloading a selected SQL NULL into an existing struct

GORM Playground Link

https://github.com/go-gorm/playground/pull/861

Description

Reloading a record leaves an old *time.Time value hanging around after the column becomes NULL.

1. Load a row with a non-null timestamp using First(&record, 1).
2. Set that column to NULL in the database.
3. Call First(&record, 1) again.

I'd expect the pointer to become nil. Instead, it still holds the old timestamp. Loading the same row into a fresh struct gives nil, as expected. No query errors.

The repro is just an ID and a *time.Time field. No hooks or custom types. Everything runs in one transaction.

Reproduced with GORM v1.31.1 and v1.31.2, PostgreSQL driver v1.6.0. The linked test fails on PostgreSQL; I haven't checked other databases.