Update hibernate core to v5.6.15.Final

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
org.hibernate:hibernate-ehcache (source)	5.6.14.Final -> 5.6.15.Final
org.hibernate:hibernate-core (source)	5.6.14.Final -> 5.6.15.Final

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Release Notes

hibernate/hibernate-orm

v5.6.15.Final

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Configuration

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