[Enhancement] [UnusedVariable] Add MockitoBean in EXEMPTING_VARIABLE_ANNOTATIONS for UnusedVariable because spring 6.2 is migrating from MockBean to MockitoBean.

[alexandrenavarro]

[ENH] [UnusedVariable] Add MockitoBean in EXEMPTING_VARIABLE_ANNOTATIONS for UnusedVariable because spring 6.2 is migrating from MockBean to MockitoBean (see https://docs.spring.io/spring-boot/api/java/org/springframework/boot/test/mock/mockito/MockBean.html).

I made the PR #4800