tech-debt: mockito-core >4 requires Java 11 minimum

[Zidious]

Note: this is a test dependency so its not urgent

As of mockito-core 5 they require a minimum version of Java 11. According to their v5 release notes:

What should I do if I still run JDK 8?
For JDK 8 and below, you can keep on using Mockito 4.
This is similar to if you are using JDK 6, for which you can keep on using Mockito 2.
The changes in Mockito 5 (for now) are primarily focused on the latest JDK versions, which means the API differences between Mockito 4 and 5 are minimal.
However, over time this will most likely widen, so we do recommend adopting JDK 11 in the future.

[Zidious]

No longer required