Update to spring boot 2.7.5 and Java 17

Hi, Thank you for sharing this project. This is a great example of DDD.

I tried to update the project to spring boot 2.7.5 as a transition to 3 but I ran into an issue with archunit.

io.pillopl.library.lending.architecture.NoSpringInDomainLogicTest is failing:

Architecture Violation [Priority: MEDIUM] - Rule 'no classes that reside in a package '..io.pillopl.library.lending..application..' should depend on classes that reside in a package 'org.springframework..'' was violated (7 times):
Method <io.pillopl.library.lending.book.application.CreateAvailableBookOnInstanceAddedEventHandler.handle(io.pillopl.library.catalogue.BookInstanceAddedToCatalogue)> is annotated with <org.springframework.context.event.EventListener> in (CreateAvailableBookOnInstanceAddedEventHandler.java:0)
Method <io.pillopl.library.lending.book.application.PatronEventsHandler.handle(io.pillopl.library.lending.patron.model.PatronEvent$BookCheckedOut)> is annotated with <org.springframework.context.event.EventListener> in (PatronEventsHandler.java:0)
Method <io.pillopl.library.lending.book.application.PatronEventsHandler.handle(io.pillopl.library.lending.patron.model.PatronEvent$BookHoldCanceled)> is annotated with <org.springframework.context.event.EventListener> in (PatronEventsHandler.java:0)
Method <io.pillopl.library.lending.book.application.PatronEventsHandler.handle(io.pillopl.library.lending.patron.model.PatronEvent$BookHoldExpired)> is annotated with <org.springframework.context.event.EventListener> in (PatronEventsHandler.java:0)
Method <io.pillopl.library.lending.book.application.PatronEventsHandler.handle(io.pillopl.library.lending.patron.model.PatronEvent$BookPlacedOnHold)> is annotated with <org.springframework.context.event.EventListener> in (PatronEventsHandler.java:0)
Method <io.pillopl.library.lending.book.application.PatronEventsHandler.handle(io.pillopl.library.lending.patron.model.PatronEvent$BookReturned)> is annotated with <org.springframework.context.event.EventListener> in (PatronEventsHandler.java:0)
Method <io.pillopl.library.lending.patron.application.hold.HandleDuplicateHold.handle(io.pillopl.library.lending.book.model.BookDuplicateHoldFound)> is annotated with <org.springframework.context.event.EventListener> in (HandleDuplicateHold.java:0)

How should I handle this?

Start with NoSpringInDomainLogicTest and the reported handlers: CreateAvailableBookOnInstanceAddedEventHandler, PatronEventsHandler, and HandleDuplicateHold. Run the failing architecture test against the proposed Spring Boot 2.7.5 and Java 17 versions, then determine how the EventListener dependency should be handled. Done means the upgrade is applied and the architecture test passes without weakening its stated rule.