add --temp-dir option to umitools dedup

[kopardev]

https://github.com/RBL-NCI/iCLIP/blob/201bfb96d3b205a6bd7c6f67a5ed1f1e9828d518/workflow/Snakefile#L1420

umitools dedup sorts the output by default (see https://umi-tools.readthedocs.io/en/latest/reference/dedup.html#no-sort-output) so provide it with a --temp-dir as recommended to save temp files.