update MuTect2 with gatk 4.1.2.0 inputs

The "--f1r2-tar-gz" input is used in FilterMutectCalls (check: https://gatkforums.broadinstitute.org/gatk/discussion/24057/how-to-call-somatic-mutations-using-gatk4-mutect2#latest).
The "---germline-resource" input was already available in gatk 4.1.0.0.