Update hibernate core to v5.6.15.Final (mulk/mulkcms2!17)

This MR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [org.hibernate:hibernate-envers](https://hibernate.org/orm) ([source](https://github.com/hibernate/hibernate-orm)) | build | patch | `5.6.14.Final` -> `5.6.15.Final` |
| [org.hibernate:hibernate-entitymanager](https://hibernate.org/orm) ([source](https://github.com/hibernate/hibernate-orm)) | build | patch | `5.6.14.Final` -> `5.6.15.Final` |
| [org.hibernate:hibernate-core](https://hibernate.org/orm) ([source](https://github.com/hibernate/hibernate-orm)) | build | patch | `5.6.14.Final` -> `5.6.15.Final` |
| [org.hibernate:hibernate-jpamodelgen](https://hibernate.org/orm) ([source](https://github.com/hibernate/hibernate-orm)) | provided | patch | `5.6.14.Final` -> `5.6.15.Final` |

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### Release Notes

<details>
<summary>hibernate/hibernate-orm</summary>

### [`v5.6.15.Final`](https://github.com/hibernate/hibernate-orm/compare/5.6.14...5.6.15)

[Compare Source](https://github.com/hibernate/hibernate-orm/compare/5.6.14...5.6.15)

</details>

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