test: Add Simple SLF4J binding to unit tests runtime

[valfirst]

Change list

Add Simple SLF4J binding to unit tests runtime: https://www.slf4j.org/manual.html#swapping .

Types of changes

What types of changes are you proposing/introducing to Java client?

• No changes in production code.
• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Details

This change fixes the following error:

    SLF4J: No SLF4J providers were found.
    SLF4J: Defaulting to no-operation (NOP) logger implementation
    SLF4J: See https://www.slf4j.org/codes.html#noProviders for further details.