Fix SLF4J config for logger in unit tests

The following warnings are currently being logged by the CI unit tests:

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.google.refine.sampleExtension.SampleUtilTest
SLF4J(W): No SLF4J providers were found.
SLF4J(W): Defaulting to no-operation (NOP) logger implementation
SLF4J(W): See https://www.slf4j.org/codes.html#noProviders for further details.
SLF4J(W): Class path contains SLF4J bindings targeting slf4j-api versions 1.7.x or earlier.
SLF4J(W): Ignoring binding found at [jar:file:/home/runner/.m2/repository/org/slf4j/slf4j-simple/1.7.36/slf4j-simple-1.7.36.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J(W): See https://www.slf4j.org/codes.html#ignoredBindings for an explanation.

Not sure if this is something inherited from the core or specific to this rep