Fix SLF4J config for logger in unit tests #54

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[INFO]  T E S T S
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[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.