Minor typo in log file for single-end kallisto

Line 253 in the snakefile with single_end rules states:
os.path.join(config["log_dir"], "single_end", "{sample}", "genome_quantification_kallisto.log.log")

There is a duplication of "log" I have noticed while parsing results for the report. I think this is minor enough to be fixed directly in master, no need to branch off...