The return values of the update function (object '_previousDataValues' and 'dataValues') seems incorrect.

Issue Creation Checklist

• I understand that my issue will be automatically closed if I don't fill in the requested information
• I have read the contribution guidelines

Bug Description

After changing the data using the UPDATE function with returning and plain set to true, the return data _previousDataValues and dataValues shows the same data, and not the data before and after the update.

Reproducible Example

What do you expect to happen?

The object _previousDataValues should contain the value before the update.
In my exemple, the console.logs (of title) should show different values (before and after update)

What is actually happening?

The object _previousDataValues shows the same values as the object dataValues and those are the new value after the update.
In my exemple, the console.logs (of title) should show the same values

Environment

• Sequelize version: sequelize@6.35.2
• Node.js version: v20.18.1
• If TypeScript related: TypeScript version: Using javascript
• Database & Version: PostgreSQL
• Connector library & Version: pg

Would you be willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time and I know how to start.
• Yes, I have the time but I will need guidance.
• No, I don't have the time, but my company or I are supporting Sequelize through donations on OpenCollective.
• No, I don't have the time, and I understand that I will need to wait until someone from the community or maintainers is interested in resolving my issue.

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Reproduce the issue with Sequelize 6.35.2 on Node.js 20.18.1 using PostgreSQL and the pg connector, calling the update function with returning and plain set to true. Inspect the update path and verify that the returned object's _previousDataValues retains the old title while dataValues contains the new title.