Bump hibernateVersion from 5.4.33.Final to 5.6.15.Final

Bumps `hibernateVersion` from 5.4.33.Final to 5.6.15.Final.

Updates `org.hibernate:hibernate-entitymanager` from 5.4.33.Final to 5.6.15.Final
- [Release notes](https://github.com/hibernate/hibernate-orm/releases)
- [Changelog](https://github.com/hibernate/hibernate-orm/blob/5.6.15/changelog.txt)
- [Commits](hibernate/hibernate-orm@5.4.33...5.6.15)

Updates `org.hibernate:hibernate-core` from 5.4.33.Final to 5.6.15.Final
- [Release notes](https://github.com/hibernate/hibernate-orm/releases)
- [Changelog](https://github.com/hibernate/hibernate-orm/blob/5.6.15/changelog.txt)
- [Commits](hibernate/hibernate-orm@5.4.33...5.6.15)

---
updated-dependencies:
- dependency-name: org.hibernate:hibernate-core
  dependency-version: 5.6.15.Final
  dependency-type: direct:development
  update-type: version-update:semver-minor
- dependency-name: org.hibernate:hibernate-entitymanager
  dependency-version: 5.6.15.Final
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pom.xml

@@ -53,7 +53,7 @@
         <test-forkCount>1</test-forkCount>
         <cassandraVersion>3.12.1</cassandraVersion>
         <cassandraUnitVersion>3.11.2.0</cassandraUnitVersion>
-        <hibernateVersion>5.4.33.Final</hibernateVersion>
+        <hibernateVersion>5.6.15.Final</hibernateVersion>
         <h2Version>2.5.250</h2Version>
         <pmd.failOnViolation>false</pmd.failOnViolation>
         <aws.java.sdk.version>2.21.20</aws.java.sdk.version>