Consider lowering required Java version to 8

[mikemybytes]

As for now, Java 11 is the oldest version supported by the library. As JUnit 5 targets Java 8+, it might be worth downgrading the library codebase to Java 8. Yet, the implementation relies on some newer APIs (like java.util.regex.Matcher#results()) that will require proper replacement. Additionally, as the usage of versions < 11 drops, such effort may not be worth it.

[mikemybytes]

There were no complaints about Java 11+ requirements so far. As most of the upcoming major frameworks versions (like Quarkus 3 and Spring Boot 3) will require at least Java 11 as well, it feels like a good idea to leave it as a baseline here as well.