fix slf4j multiple bindings on classpath warning
fix slf4j multiple bindings on classpath warning

exclude slf4j-jdk14 backend in order to prevent a runtime warning
fixes #1063

frank-y-liu/gatk,magicDGS/gatk,frank-y-liu/gatk,ksthesis/gatk,frank-y-liu/gatk,ksthesis/gatk,ksthesis/gatk,broadinstitute/hellbender,broadinstitute/hellbender,ksthesis/gatk,broadinstitute/hellbender,broadinstitute/hellbender,magicDGS/gatk,frank-y-liu/gatk,magicDGS/gatk,magicDGS/gatk,ksthesis/gatk,frank-y-liu/gatk,ksthesis/gatk,frank-y-liu/gatk,magicDGS/gatk,broadinstitute/hellbender,broadinstitute/hellbender,magicDGS/gatk