Support Spring Boot 3

[MarekLuthardt-Sixt]

The current implementation is not compatible with Spring Boot 3, which has migrated from javax.* to jakarta.* - causing the following error:

class org.springframework.orm.jpa.persistenceunit.SpringPersistenceUnitInfo cannot be cast to class javax.persistence.spi.PersistenceUnitInfo (org.springframework.orm.jpa.persistenceunit.SpringPersistenceUnitInfo is in unnamed module of loader java.net.URLClassLoader @330296c5; javax.persistence.spi.PersistenceUnitInfo is in unnamed module of loader org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader @1d9ccf6f)