AnnotationTypeMapping warning when using @EnableRetry with Spring Framework 6

[hpoettker]

Any Spring application that uses the annotation @EnableRetry with Spring Framework 6.0.0 and Spring Retry 2.0.0 logs the following warning on start-up:

WARN org.springframework.core.annotation.AnnotationTypeMapping [main] : Support for convention-based annotation attribute overrides is deprecated and will be removed in Spring Framework 6.1. Please annotate the following attributes in @org.springframework.retry.annotation.EnableRetry with appropriate @AliasFor declarations: [proxyTargetClass]

This PR does what the warning kindly asks for.

The warning can be seen easiest when executing EnableRetryTests.

I've also assembled a reproducer. It's a plain Spring Boot app with the annotation: https://github.com/hpoettker/alias-demo

[garyrussell]

@hpoettker Thanks for the contribution!